Microsoft had a very specific niche of making completely awful software that wasn't actually broken - in fact, that was often the infuriating thing.

If it just shat the bed completely, you'd have an easy argument to replace it with something else; instead, it would be technically competent (Hi, Raymond!) but covered in stuff that made it infuriating to use (Hi, Redmond!), especially if you didn't live in it day in and day out.