Well then lets move Federer a lot further down the list too since he won all his slams in the same era.
This surface homogenization thing is nonsense - yes it's more homogenized but there is no way Rafa won those slams playing just like he does at RG. He had to make quite a few adjustments on grass - much better serve; better net skills; be more attacking; stand further up on the baseline... Just because it wasn't serve & volleying doesn't mean it was the same. Same for US Open - he had to get a much better serve & be more aggressive. If they're all the same then the claycourters who do well at RG like Almagro etc. would have similar success elsewhere but they don't. And finally the conditions are the same for ALL players in this era - why have only a few benefited? Perhaps because there are still differences and only a few like Fed & Nadal and now Novak & Murray are the best at adapting their games? Tell Roddick - the multiple Wimbledon finalist that RG plays exactly the same...
Federer's game is different than Nadal. He has an attacking mindset and looks to dominate the opponents. In short he has a riskier game than Nadal.
With these surfaces it has benefited the player who takes lesser risk and in this case its Nadal who has benefitted.
Somewhat similar analogy, in the 1950s and 60s it favored the players who S&V and who had better volleys and touches. And in that case it was Rosewall who benefited the most because his game suited the conditions perfectly.