I highly, highly, highly doubt any of the riders endorsing the fancy stirrups need them. They endorse them because they tried them, they agree that it certainly won't harm anyone's riding, has a good chance of helping the average rider AND most importantly... the manufacturer of said product pays them a buttload of $$$ to use and endorse them!
If someone offered me a wheelbarrow full of cash to use their product and it worked as well or better than what I was currently using...I'd be all for it! Who wouldn't!?