I think a lot of guys at the club level could benefit by flattening out their forehands. The average person is not built like Andreev or Nadal. For us mere mortals that can generate only so much racket head speed, There's a choice about how much of that needs to go into spin to bring the ball up and down, and how much of it need to go into the flat penetrating aspect of the shot.
A lot of guys at the club level hit short spinny balls that sit up waiting to be crushed and think they are copying what they see on tv.
Look at a player like Davydenko. He's not the biggest guy in the world. He hits his ball a little flatter than some of the other guys. It allows him to play a very aggressive game.
Everyone should find a playing style that suits them. That being said, some of the wta takebacks on their forehands are so ridiculously ugly. A lot of the younger women on the tour are not using the Sharapova/Serena style takeback. More of the up and coming players have more atp style takebacks.