Can we lets say, pick 3 roles as our favorite role, and every game we play, we get slightly higher chance of getting those roles?
Also, as an expansion to that, everyone hates some roles, so another option would be to choose the least favorite role, in order to decrease the chance of getting it.
Edit: To get around the problem when one player is known to play good or evil role, would be to force players who use this feature to use default (random) name, or alternatively force them to use a different chosen name each game.
I would argue that in theory the ‘known evil’ problem sounds bad, but in practice it wouldn’t be common at all, as well as, once somebody gets killed for being a known evil, he would learn himself that he should use different name each game and would solve the problem on his own, therefore if this will be a problem it will only be a problem for a short time after release of the feature.