I suspect they wanted it simpler (in the sense of things like not having to worry about giving the wrong card to a damage dealer and screwing up their rotation) but also wanted to address the "fishing for Balance" issue. This isn't about whether whichever AST is reading this comment thinks such things were issues in need of fixing, but SE apparently did.
And to that point, anything that gives straight damage will be sought after by many players. Even if the math says some higher value on another buff would technically yield slightly bigger deeps. It's a mentality that's hard to break. Rather than just removing Balance, they made everything Balance.
Would like the new system better if used a mix of things other than a direct % damage buff and you needed particular hands to get longer durations or other enhancements to the buffs. The system would still simpler, have a smaller "risk" for poor card management, and yet let a player try to build a good hand as part of a mini-game.
After drawing you’d have a choice to stick with and “spend” one card (which would always have some appreciated bonus), try to stack a second card (which could add some enhancement of the first card or a new effect but that may not be the best combo, so basically better than just the first card but not by much), or try to stack a third card.