Holding money in a foreign account doesn't restrict Apple's spending on R&D in any important way. Apple holds stock in foreign accounts and issues bonds. They have plenty of cash to fund R&D anywhere and if they didn't they can issue bonds. This is like the argument: if I can balance my checkbook, why can't the government. Governments and modern corporations don't work like your checkbook account.

Allowing repatriation would bring at least $2 trillion in capital back into the U.S. These are profits earned overseas, and trapped there because you lose half of them to taxes if you try to bring them back to the U.S. Bringing it back means a tidal wave of dividends and increases in bank capital, which are reinvested and lent to US businesses to make them more productive and create better jobs.

If you really think that money sitting in bank accounts, stocks and bonds does nothing, you simply don't understand anything about the economy. Doing it the U.S. instead of Ireland or the EU is a big deal.

  These are profits earned overseas

These are profits earned worldwide which have largely been laundered overseas (e.g. the infamous "Double Irish").