I'll often try to check in earlier than planned, esp. if seeking an upgrade. In return, I'll tell the desk staff that I'd be delighted to wait in the lobby or run some errands, so that the hotel can have some time to see if a nice upgrade is available and ready it without undue pressure. (Often times, the upgraded rooms aren't ready 'til later as the elite previous occupant may have used an elite benefit of late checkout.) In my typical case, I'm at the hotel's bidding as I don't have the early res. confirmation and expectation you had.
That said, I never feel an obligation to spend for food and drink just to pass the time and I've never had the hotel expect I do so.
What I would have recommended in your case is to have asked to speak with the manager at the first step when you were told your room was not ready, to explain the steps you took to secure the res. for the time you needed to occupy and to explain that you assume the manager can meet your reasonable expectation. In similar cases, I've had when room readiness has clearly lagged the hotel's protocol, the manager has often extended him/herself to expedite room readiness without me having to feel obligated to purchase food and beverage.