Trademark litigation can be expensive, but you can't win every trademark case just by throwing more money at the problem. If there was a legitimate IP violation then someone would have won a case against Google by now.
The idea that I can buy placement in searches for a competitor is not clearly a "legitimate IP violation" but I think it's also not clearly "not a legitimate IP violation".
Is it good for society that I can redirect users who intend to be looking for a competitors' products? Its a complex subject that I'm not sure the courts have examined the repercussions of properly. The counterfeit and deception arguments in some of the suits certainly seem like they have some merit to me.
Courts are responsible for interpreting the law, not for considering repercussions. If you think the current situation isn't good for society then take that up with the legislative branch, not the judicial branch.
Looks like several companies have tried to sue Google for this, but Google threw a lot of money at the problems to prevent them from winning.