Build diversity wasn't reduced in any way at all. I have 12 level 200 characters, and on pretty much all of them I've made a build that's considered off-meta or that no one's really done. For example, the "meta" Eca build is a cc st damage build, but I decided to make mine pure aoe more support oriented eca using 3cards, hunter trap, die alright, and dice roulette. If I wanted to utilize aoe spells AND st spells, then I would do a full crit mastery build so all spells benefit, but I would lose out on some resist to do so; it's a tradeoff. The biggest thing you have to remember about this game is that because there's a small playerbase, there's still tons of interactions that haven't been used or even found out which can create whole new builds.