First, it doesn't change the fact that the amount of available silicon is limited. Instead of every card potentially becoming a gaming card now only a subset of them will, with the rest going exclusively to miners. How is that a good thing?
Second, it kills the second-hand market. Remember a few years back when used mining cards flooded the market and you could get a decent GPU dirt cheap? Yeah, NVidia didn't like that. Well, this won't happen anymore with those mining-only cards, since they're useless for anything other than mining. More e-waste, yaaay.