UI Designers don't give a rip about Fitt's Law or any of these self-proclaimed design "laws". Unless it's a useful authority to appeal to for beating opposing UI Designers.
That's exactly the problem, UI redesigns are almost never based objective arguments. Instead they are driven by fads and the personal preferences of whoever wins the internal argument, with users caught in the middle.
Software going through massive redesigns every couple versions should be seen as a huge negative. If the last redesign was so bad it needed to be replaced so soon, why should I trust the new one to be any better? Instead these changes often get trumpeted.
