I think the hype is value. There are a lot of places that sell cheap stuff, but I think IKEA sells better looking cheap stuff at an acceptable quality level. For example, you're not going to get solid oak bookshelves there for $150, but you can get attractively stained and finished solid wood bookshelves. Plus most stuff is well designed (ie, someone actually thought about the purpose of the item and designed for it) IMHO. Not everyone wants a $3000 entertainment center or desire a $300 Sauder fake wood stuff, though a lot of IKEA stuff is fake wood but in a lot of styles.
