Roster diversity

Since a lot of players are constantly complaining about the lack of roster diversity, I have a clever idea...similar to the idea of achievements, make goals or targets for different characters being used in pvp events which once triggered gives you some worthwhile rewards, for example, use bagman in 20 victories in pvp...reward 10 pack heroic...or even pairs of characters used, or use 3 xmen, use 3 avengers...etc. i think this would help.