Is that really the case? Apart from the obvious "maybe that's what they're intrinsically interested in" - if you start with a problem, try to solve it, and "pure mathematics" (whatever exactly that is supposed to be, anyway) is required to arrive at a solution, it becomes part of the intrinsic motivation. And if you keep solving problems without it the question that eventually comes up is "is it really useful at that point?"
I do however agree that if you're looking at someone who's qualification is primarily his "portfolio", you do actually need to check whether it includes interesting problems, or at least projects that are related to what you need them to do at your company. But if that is the case, I really don't see a problem.