I'm not going to make suggestions that have no chance of being implemented IMO, so some obvious ones I'll ignore. But two changes would go a long way with me:
Re-rolling -- Please change re-rolling to not have a progressive cost increase. All that does is create an unnecessary sense of anxiety that through bad luck you might be priced out of getting the composition you want. That's a frustrating experience and one that I'm hearing about a lot from other players.
Team Relic Requirements -- Please remove the team relic requirements. This is extremely limiting and makes us not want to interaction with datacrons. Any toons below the threshold should simply not get the benefits (similar to how DS toons are with LS datacron bonuses), rather than detracting from the rest of the team.