I can understand their reason for "fixing" it, as many didn't like that it wasn't 100% consistent at doing one thing or the other, and that makes sense.
But considering a lot of guns do it at least occasionally, and plenty of folks appreciate that M&Ps were pretty consistent at doing so, I'd rather they offer a "fixed" slide stop that could be swapped in, instead of making all M2.0 models use the "fix".