Those rubbery, calculator type keyboards in several early computers at 80's were really bad. But I dont understand at all, how Commodore 64 is on the list (10th worst) I strongly disagree!
And I have typed many, many program listings, used wordprocessor and spreadsheet with my C64.
I would say, any relatively new el-cheapo keyboard that has a 'spongy feel' when pressing the key is worse, and what's also annoying, is that nowadays the manufacturers are making the keyboards smaller (people dont have space on their desks anymore?) so the keys are too close to each other.
At work I have a HP keyboard from circa -08, that is clearly 'downsized', and many times after I've once again hit two keys at the same time, at the end of the day I've been very close to yanking that keyboard off, and to bring next day some older, real sized keyboard from home to replace it.
Oh, and yes, those 'ergonomic keyboards', as mentioned before, they are really awful.