The key word here is sell. If readers wouldn't buy it, the publishers wouldn't publish it. So it's actually the readers faults. In the end, though, I don't see where celebrity sales really hurt a lot of other writers. The market for celebrity books and the market for, say, literary fiction or mystery novels would be very different, I'd think. Even in the market for memoirs and biographies, I don't think it can be said that celebrities have taken it over. Memoirs like "Angela's Ashes" have done pretty well in the past as well.
As to the general topic of this thread, I think it's great to write for yourself. But if you want to get published, then you have to think about readers. Otherwise, what's the point? The thing is that if you are only writing for yourself, then you should only expect one reader: yourself. The problem I have is when writers say that not only should they not care what anyone else might think of their work, but that when they finish their work those same people whose opinions they insist don't matter, are supposed to grab up the manuscript and publish it. If you don't want to write to communicate with anyone else, then don't get mad when other people don't want to read your work.
On the other hand, I think it's definitely possible to write both work that you enjoy and that meets your own quality standards as well as work that aims to communicate with an audience, and that succeeds. In my estimation the quality of a lot of popular authors' works is overlooked by people who make the assumption that a book with depth can't also contain a good story and attract a large audience.