I agree with some of the points in your initial post, but disagree with others.
Federer's game is more aesthetically pleasing. Yeah, yeah, beauty is in the eye of the beholder and all, but most would agree on that so there seems to be a consensus in that regard.
However, the part about "god given talent" and all that stuff is a bit too simplistic. I hate that term anyway, but let's call it "natural talent" for argument's sake (which undoubtedly exists). Federer might be more "naturally talented" (I'm inclined to think he is), but to seriously boil it down to Federer being a product of said talent while Nadal is a product of hard work is the part I find nonsensical. These are two players who between them, have won 36 majors. 20 to 16. That's insane. I am willing to bet a year long's salary that Roger's worth ethic is out of this world. The same way I'm willing to bet a year long's salary that a player who could have played tennis with either hand and possesses one of the greatest shots in the history of the game has out of this world talent. Nadal's appearance (especially early on) and physical style (again, early on) helps the stereotype that he's all about physical athleticism and hard work, and I guess his relatively limited game early on would lend credence to that, but I am of the belief that just because you work a lot at something doesn't mean you'll get better at it. Yeah, you'll get marginally better, but to get as good as Nadal did at say, hitting the backhand, when it was so pedestrian early on (I think it's undeniable he now has one of the best backhands on tour), you have to be supremely talented.
Also, what is genius? Nadal is accepted to have one of the highest tennis IQ's in tennis, if not the highest (to me he's the best problem solver in tennis). Does that not count as genius? Or are we going with genius = touch? Because that's generally where commentators use that term the most: When a player makes some improvised shot, or a particularly optically pleasing one. In that sense, yes, Roger does this more. I think in this case, and I know I'm debating semantics, but you're talking about artistry rather than genius. Roger is definitely a better shot-maker and that's not even debatable. But to simply boil down Nadal's game to pure strength or just hitting good ground strokes is silly, and again purely stereotypical. He's much, much more than that, and this is from someone who believes Nadal's volleys for example, are grossly overrated. When you factor in shot selection, hand-eye coordination, shot-making, etc...then Nadal is a "genius," whatever that means.