My nominations for the worst designs of all time:
CD Jewel Case:
The case cracks and the hinges break on your first attempt to open it.
"fit comfortably in your ears and sound great"???--they don't sound too great to everyone within 20 feet of you on the subway or bus!
Miss Blanche by Shiro Kuramata:
Only because it is totally overrated; I was around in 1988 when it appeared and at that time it was trivial and irrelevant: somehow it has become an "icon of design"?? (apologies to Agnes Gund and Patricia Cisneros, two great ladies and true "icons" of art)