Overdesign

Everyone gets greedy from time to time, and that includes designers. When designers try to pack too many features into a product or push design principles too far, the product can end up being harder to use, more expensive, and less effective at whatever it was supposed to do in the first place... More here.

Some good examples here, in particular the coffee pot. I use a stovetop these days and it works so well despite having no moving parts at all.