I like the idea in theory and the examples you give are compelling.
However, I don't see it being much of a decision in practice. If given the option, I would always choose to use the ability that gives me the best chance of a succesful outcome. Part of the fun of BG3 is rolling with the punches; lowering the opportunities to fail would diminish that aspect of the game.
Also, I like that characters stink at some things. It helps differentiate them, and it makes a character with more evenly distributed attributes a viable build. The variant ability check rewards min-maxing in a way that's detrimental to roleplay. If you don't want your druid to be a dummy, don't make him a dummy.
