Ikea has done that for quite a while now and is ramping it up this year. The PAX wardrobe system [1] has been an IKEA staple for many years and people are very happy with it (what I hear around me). They starting to take this concept into the living room with the BESTA storage system [2] which allows people to create their own entertainment unit or cupboard. Not to mention their kitchen systems because kitchens are always a "design your own" purchase.

[1] http://www.ikea.com/us/en/catalog/categories/departments/bed... [2] http://www.ikea.com/us/en/catalog/categories/departments/liv...