The 80-20 rule and maining one role.
http://cdn2.hubspot.net/hub/66868/file-2230443915-jpg/80-20_rule.jpg
So here's a new idea. I am going to be applying Pareto's principle (If you don't know what it is, look it up), AKA the 80-20 rule, to role selection. Here's my idea:
If more than 80% of your games are played in one role (one role being 20% of all roles, since there are 5 roles to pick from), then you will have the OPTION to select only that role to be played in ranked dynamic queue.
Now, this would only slightly affect queue times, because only a small portion of the community focuses on roles this much, and it would also resolve people's complaints in champ select that they need another role. It gives them NO EXCUSE to not be playing two roles, because they clearly can play more than one role if they have more than 20% of ranked games played in other roles.