I think it depends a whole lot on what exactly you are market making and how you're trying to profit. Of course many desks take views as well, but mixing in prop positions doesn't change the essence of it: the MM is trying to make money off being available for other participants.

You can of course also learn some things about where to market is going in the course of this business, and many desks are able to piggy back on some flow information for their advantage.