The broken knees and injured thighs weren't a problem before they had this new padding, so I can't see how it would suddenly become one now that it has been taken away.
For the height thing - has anyone noticed that all of the complaints about the shorter pads on tall guys have been coming from people shorter than Roman Turek (6'4, Dunham and Snow are 6'3), who has always worn 38" pads? I think he's the tallest guy in the league (gets an exception to wear a bigger sweater because the 58 fits him like spandex), and he thinks the 38" pads are plenty long enough.
For that matter, I think I've only heard two or three whiners complain about the rule anyway, and I've heard that many publicly support it too. If Dunham wore those knee pads the way they were designed, they wouldn't have been outlawed in the first place. They are supposed to fit against the leg, not sticking out, anyway.