Because it's completely brainless. He's just telling us exactly what we're watching. I half expected him to come back after the point with "and now Roddick is straightening his socks and wiping his face with the towel. Now he takes three balls from the ball boy and chooses the two he's going to serve with." etc. etc.
I know that's not their job, my point is that their job is completely unnecessary and just clogs up the airtime to little benefit. Good television commentary enhances what you're watching, not describes it in mind-numbing detail.
You need play-by-play callers at the football when sometimes its hard to differentiate between the players without looking carefully and knowing all their names, but it's completely superfluous at the tennis where the action is self-explanatory. It reduces guys like Sandy and Bruce to repeating the score and constantly coming out with valueless nothings like "he'll be pleased to get the break" or "she's about to serve for the set".
I would literally rather listen to nothing - just the sounds of the court and the players - than their endless worthless bleatings. The only value they add is their statistics (and Bruce leaves Sandy for dead in that department) but it's nothing that a researcher couldn't do behind the scenes and then just hand to one of the experts to read out.
I don't know why Seven persists in giving front-seat billing to non-expert commentators at all their events. None of the other channels really do it unless its something like the Olympics (where it's impossible to have sufficient experts in every category).
/rant
