Ok firstly lets address elephant in the room... forts are problematic because they was designed for how the server use to be with 3 pairings open and maybe 200 players maximum on good days per a side if it was balanced. Now we get silly numbers like 800 vs 600 in one zone... and 300 defenders in one tiny lord room, and hundreds in the que. This creates numerous issues... the solution is to find a acceptable method to each of the problems.
The higher you increase the population cap the more it favours the defenders and the fort balance becomes insane and just a free farm for any defence organised or not... there will be so much bodyblock/lag and constant aoe pressure (not including morales) that taking the fortress becomes next to impossible and very defeating for the realm which does the hard work in pushing, so everyone will play the boring counter game wait for enemy to punch itself out and run out of energy / log off ... what is the incentive of pushing zones if the end result is going to be stacked unfavourably against you? If both sides sit and wait creates boring zzz stalemate rvr which is not very healthy.
There is also the problem with having gear which is padlocked behind this content... so you want it to be fairly accessable to the server when big numbers are out i understand and get this and not for people to freely skip content, but the more you increase the population cap for defenders (its very easy, i could defend any fort with 100 organised players would be overkill on either realm) this creates another problem of padlocking city content even more, and especially during high population timezones so EU gets shafted the most... where other timezones with less defenders will have a much harder time to defend and more likely lose.
So how do you solve this solution? how much do dev's want to redesign fort with new server in mind? how radical can it be?
This is just a suggestion, it might have some issues and might not even be possible... but for me forts are currently the worse part of the game, it is pure grind and funnel wars and a massive lag / crash fest and mindless napalm/rof spam... but they are the essential bridge to late game content. Would it be possible to make forts instanced at all? and reduce the population cap considerably in each fortress... so its a rough example 72 vs 48 (you can adjust as per your %) but have numerous instanced fort sieges at the same time... 3 warbands vs 2 warbands and if the attacking realm wins majority % then they lock the fortress for their realm ?
A slight issue will be win by not defending? well the first instance should always pop... then next instance should pop if enough defenders to meet criteria... so there is no empty free auto win instance for attacker (and i assume most people will want to defend/fight and get rewards (if people decide to cheese system by not defending, can always increase reward for defending if it is fair system in place on attacker). This way it should atleast feel more inclusive and your characters actions actually matter more than just zerging things down... people would need to organise que up more with proper warband setup (which would make them more ready for cities too). Less numbers can give some ST more importance instead of mindless aoe spam. At the moment we are all getting squeezed into one spot and throughout the server's history that has never really ended well with lags and crashes.
Ok if it is not possible for something radical like the above suggestion... which i think would really improve the fun factor and inclusivity. (defenders would have to earn their victories instead of just win by default which is the current status quo its too easy to defend with body block / lag and weak warband setups with only 3 healers)
Funnels... if you want to fit 300 people into one room, you need to have more access points than just two. I saw the potential of orcapult and that was fun, even if it was a test/gimmick... but it gives some MDPS a purpose more than they currently have... sit back watch rdps aoe spam, wait to push funnel and die or zerg enemy is not really fun playstyle for mdps...
Would it be possible to make more side entrances like the back postern? (still pretty easy to cover especially with 300 people)
would it be possible to widen the front entrance, and also the postern? (it will be harder for lower number pops potentially... but currently primetime becomes self defeating and that is pretty demotivating for the attacking realm and eventually boring... (why bother attack, let enemy punch themself out there is little incentive or fairness) If the above is not possible.... would it be possible to add multiple ladders on the side of the fortress to climb up to the higher levels? would it be possible to bring orcapult back as a permenent feature? we need variety / fun ways to break endless zerg / funnel wars... City is alot more fun than forts can ever be, because its about fighting if you get two equally matched sides and less slide show.
The current status quo of zerg around capture the flags on forts like nascar... build m4 push and hope for the best in lag / body block is a pretty lacklasture part of the campaign with its own knock on effects.
If we are talking about more radical revamping of forts... can we make more fun stages? like stage 1-2 is boring... can we not add event for actually breaking the outer walls? if you give enough defenders in fort they can funnel 3 outer choke points (results in same boring play as fort lord room) can we not have orcapults, and ladders to breach outer wall... or even potentially siege towers which warbands could instantly use to spawn on outer walls and storm the area ? give defenders some ballista to potentially counter some siege towers... a few siege towers should die if defenders are co-ordinated a few should breach because the attacker earnt the right to get there and needs some inniative...
Could we take some inspiration from stage 2 in cities with escorting NPCS and make this a stage in forts... if attackers get a NPC inside, can give bonus to the attackers like pulse aoe healing / pulse aoe absorbs as a semi counter for pugs and rof/napalm/pos spam and make the npc only attackable in melee on lord stage so defenders would have to come out to kill it if they want those benefits gone if they didn't kill it previously on escort stage.
next stage capture the flags... it is benny hill, maybe some more importance can be placed on fighting and killing? if attackers reach X amount of kills first then the lord or mechanic on final stage should be weaker (or diminishing rations as their supplies cut off) ... if defenders reach X amount of kills before attacker then give them oil (non respawnable) for both main inner, and upper main lord room (non respawnable) just some minor incentive for fighting and reward for whoever does better during this stage...
Lord stage... is it possible to reduce his agro range and make it more about the PVP over the PVE?
If you can make forts instanced and lower population per a fort instance... no need to add extra entrances... but if you want one big cluster zone fortress then there needs to be more even playing field for the attacker and not just a simply stand still aoe on 2 entrances where your own realm is going to get in your way more than the defenders actually do anything significant or noteworthy...
Anyways thankyou for reading... it was just some suggestions which hopefully can maybe spark and produce better ideas that lead to a better system than the one we have currently which is problematic and outdated as it was designed for smaller numbers than the masses we have now... and if invader is only way to get sovereign we really need a useful long term solution which is fun/fair on attacker and is in line with Dev goals and tools available for the campaign.
Cheers
Wam
Spoiler:
usually its not , even if equally matched , realms are unbalanced ( you said that yourself ).
Cities are still taking place daily , why the hurry for it ? Also , JAIL and POISON mechanics didnt get a mention and they are very decisive in forts and i mean VERY .In conslusion and always in my pov, forts are ok to me( poison mechanics included ). Yesterday destro was pushing Reikland ( mega lag bomb locked the zone ) before they were on the Lord , 2 organized guilds ( PnP Fmj ) went and ninja capped KV and took an empty Stonewatch + threw the poison , just to make sure.. 
