Modern Elmo,
I agree with you, but here's the rub: targets can nearly always be hardened a bit more. (Another 6 feet of earth on top, say). So, you end up needing a 2,500 lb bomb. Or a 3,000 pounder. Or a 'Tallboy'. Or a 'Grand Slam'. And so on....
If you really want to 'reach out and touch' a target, capturing it and using demolition charges is often the most reliable way to do the job. Yes, more risk and harder to do, but dropping airborne explosives on to hardened targets is often an inefficient process.
'Air power' is not always the best option. Sometimes it is, sometimes it's not.