If the former, then you probably need to re-think what would happen if the system was set up a different way (i.e. something other than a order-unity fraction of the total amount). The defendants in a case like this are always going to willing to pay a significant fraction (e.g. 20%) of the potential settlement in lawyer fees in order to fight the suit. If the plaintiffs can't spend a similar amount, they will be at a serious disadvantage in court. These fees are merely a symptom of the (alleged) problem that court outcomes depend so much on lawyer fees. If you want to fix the problem, you need to change the court process; attempts to limit class-action fees will just aid the large corporations.
If the latter, then you just want the court to pay out more money to the plaintiffs. But remember: having the plaintiff lawyer fees directly proportional to the settlement is an excellent motivation for the lawyers to win the biggest settlement they can for their class-action clients.