Sampras thought about changing his racquet later in his career and he regrets it to this day. You could argue this entire forum is moot, if we are to silence ourselves based on the probability that our suggestive fodder is unoriginal.
I think for the same reason I critique Roddick's backhand slice approach shot, nadal too is in a bit of a predicament. To make systemic changes in game play just for one player is not easy, as you said, "execution is something else" ; but Federer did it for two, bullying just about everyone else. And it isn't just execution, I could be completely wrong, the team may have tried it in practice and feel it would not be effective.