For the OP (Sparkle) - I'm told that the bouncing thing is just a routine they get used to doing before a serve, to help gather their thoughts, 'focus', and remember their plan for the coming point.
Serving in pro tennis is a top priority, so they need that routine and rhythm to try and make it work to best advantage (no pun!). And that's why they sometimes chuck it up, but don't serve, if they immediately know the ball won't be quite where the racket is intended to hit it.
If you saw the coverage of the Eastbourne tournament (week or two before W'don), that was pretty windy, and lots of serves had to be stopped in that way!
Oh, and the ultimate in bouncing annoyance was surely Nadal, his routine was something like 15 bounces, scratch ear, pick nose, 8 more bounces, tug shirt, extract shorts from his derriere, 7 more bounces, flick hair back, scratch the ear again, couple more bounces, and serve. If anyone in the crowd coughed or something, he'd glare at them, then have to go back and start again, as he'd lost his place.
As has been said, they have a time limit now, between each point, if that had been used when he was playing, he'd have been chucked out of every match?!