Simpler? Definitely not.

Interest rates are controlled by the Federal Reserve, which is an independent entity that can change interest rates without needing any kind of approval from the federal government. It's very simple for them to actually implement once the decision is made.

Taxes need to be voted in by citizens, or more accurately, the representatives of the citizens. Citizens do not tend to enjoy enforcing more taxes on themselves, and representatives tend to want to get re-elected, so they have incentive to avoid raising taxes and upsetting their constituency, even if they know it's a good idea in the long-run.