I use what Federer uses cause he is my IDOL! haha, No seriously I use a 90" cause it's the only racquet I can use where I can keep my balls in the court, swing away, and win matches. I started out using the APD cause I wanted to hit massive topspin like Rafa, haha that didn't last long, switched to the 95" Ncode after my friend let me borrow his, but I found that one still wasn't right. Tried another guys 90, and magically all my shots were going in the court, I can hit as hard as I wanted and as long as I had good footwork, racquet face control, and a smooth swing, it was bombs away.
I've tried hitting with my friends Pure Drive, and I can't keep more than 2 shots in the court during a warm up rally. When we play matches my friend wins most of them, but not cause of his 100" frame, he's been playing tennis since he was a kid, and was #1 singles on his HS team. I started playing after turning 20 and learned my strokes from watching TV and YouTube LOL.
So back to the topic of why I think a lot of players use small head sizes. What I see when I go out of the courts is players buying and using racquets that help them win. Out here at the rec level, winning is all about CONTROL.
Smaller head = More Control
More Control = More Win
More Win = ???
On a side note, here is a vid where my buddy takes a shot to the head for shying away from the ball.http://www.youtube.com/watch?v=xjYaNk62zyQ