If Apple wouldn't have made the WiFI/cell switching default without warning, there wouldn't be nearly the same concerns. But it's a hidden change to many users. Not the same thing at all as a user deliberately choosing to allow a download while on cellular data.
IMHO... Apple did this LONG ago, like right from the first iPhone. And that made much more sense back then, given the data plans and data charges and small app sizes. They just can't be bothered to make a change that has become more relevant given larger data plans and larger apps.
In any case, Apple does what it does, and our opinions doesn't matter too terribly much. Just keep sending our money to them, and it's all good.
C