First, low-skill players are not neccesarily casual.
Second, for those low-skill players to improve they must have a place where they can improve, and if we want players to dedicate their time and effort into Ranked (both of which are required in copious amounts) then we must give them a reason for doing so.
Third, apparently getting farmed by high-skill players and receiving nothing in return that could not have been gained elsewhere (and better) is not something people enjoy. Hence, no one queues Ranked. Zero matches Solo Ranked played in pre-season 3, and only a handful Group Ranked.
When will you realize that ignoring these tenants of game design and player behavior is not going to turn Ranked into the success we all want it to be?
Sorry to say it, but the elitist approach you seem to be advocating is the problem. It alienates the majority of players that would otherwise be interested in Ranked, even though Ranked needs these players to succeed.
Further, I think there's a serious bias within the Ranked community against people who perform poorly. It's important to understand that no matter how elite the Ranked community might think of itself, poor performance is always a combination of the player's individual skill in relation to the competition. No matter how elite, someone will always be last. However, that someone may still be better than most of Return of Reckoning's playerbase.