But you can't dismiss the fact that some of the best rivalries in the 90's were between them (Seles vs. Graf) as pretty much agreed in the other thread. Although it is true that Monica Seles introduced the power factor into the game of tennis with her mighty two-handed play, by no mean was she just smacking the ball on the court. Furthermore, you are trying to get to your point by discarding the Grand Slams and tournaments that Seles have won over her career.
Talent my friend, can get you so far in your tennis career, people also said that Anna Kournikova have talent, but where is she now? Without determination and practice, talent will not get you anywhere. Furthermore, it all comes down to the survival of the fittest on the court, men or women. In the survival process, you do whatever that's necessary whether it's one-handed or two-handed. At the end, your opponent is not going to care about whether you have a one-handed or two-handed backhand (or forehand), all they care about is winning.
To me, tennis is an art form, it is an art of strategic style and execution, much like paying chess. While one-handed backhand does look beautiful when executed correctly, that doesn't mean it is beautiful in terms of strategic execution even for great strategists like Federer.
Shot selection wise, once again you do whatever you need. Ultimately, you are not trying to impress the crowd out there by hitting all these beautiful one-hander, you are to win. Greats like Martina Hingis, Lindsay Davenport have a lot of shot selections, but they have two-handed backhand, and Martina is agreed to have one of the best shot selections in the game.
One-handed backhand, in theory, doesn't necessary give you more edge over two-handed backhand other than the fact that you can reach further with one-hander. But with foot speed and correct footwork, you can make up most of that. (If there are any coaches out here, please correct me if I am wrong) In addition to that, one-hander can provide excellent top spin. But with two-handers, it can also provide enough top spin for control. Let's take Martina Hingis again for example, in her match against Maria Sharapova in the Tokyo Pan Pacific Open in February, she didn't need to reach much as her footwork and foot speed and even shot selection did most of the reach for her.
In conclusion, the choice between one-hander and two-hander is purely preference and needs. Your view on it is entirely in terms of being a fan. But if I were to put you out competing in the professional circuit, then you will realize soon after that one-hander or two-hander isn't that much different. Because at the end of the day, you either win or loose to a one-hander or two-hander, but you still win or you still lost. So I guess that doesn't make much of a difference.