I suppose it could also be said that spending time designing relational schemas that will change drastically, then migrating data every time they do, is wasteful. Many non-relational databases allow quite a bit of flexibility in terms of incrementally changing structure as you learn about your business needs.

Not that I am in one camp or the other. We use both relational and non-relational databases where it makes sense. The more of each (both in choices and users), the better, so far as I am concerned.