Practically, with the low interest rates, cash isn't worth a whole lot to an average Fortune 500. You can already see how Apple is getting heat for having so much cash on hand, only reason there isn't more is that people are hoping for a tax repatriation holiday. With most large companies being a) well capitalized already and b) able to borrow large amounts cheaply, you have to make a really hard case that holding onto cash (or spending it internally) is the best thing to do.
Funneling all profits back to the shareholders is only a duty when there isn't much else to do with the cash, which is mostly what's happening.
Profit is a financial benefit that is realized when the amount of revenue gained from a business activity exceeds the expenses, costs and taxes needed to sustain the activity. Any profit that is gained goes to the business's owners, who may or may not decide to spend it on the business.
Funneling all profits back to the shareholders is only a duty when there isn't much else to do with the cash, which is mostly what's happening.