I've had some pretty awful hotel breakfasts that would have cost and arm and a leg had I paid for them. However, one thing hasn't been mentioned yet, and that is small children.
Since we've had our little one, 'venturing out' on an empty stomach is much more of an ordeal, and we will either get the hotel breakfast (if either reasonably priced, included in rate or due to elite benefits, or spectacular) or try to get a few simple items and a fridge in our room. Not always possible.
tb