The FinancialRounds does a good job of explaining why capping is not a solution:
"we have to have some mechanism to allocate the available gas among the people
who want it. You can do it by lottery, by government fiat (i.e. you get a
"ration card"), by random chance, by staying in line, or by market mechanisms
(i.e. prices)....If supply decreases (say, following a hurricane), prices rise. If they rise high enough, you might decide that it's not worth it to drive to your favorite restaurant, and instead you might choose to drive to one closer so that you have more money to spend on other things. This leaves more gas available to the folks who place a higher value on it.