Nearfield listening to quiet music from efficient, non-reactive speakers might only use 5W - and there's plenty of folk who pull this off daily, with tube amps. Some of those systems top out at 10W/ch, and do a wonderful job if you're into that sort of thing.
Inefficient, reactive speakers filling a room with complex sound at reasonable volume - a common situation for audiophiles - will frequently demand much more. Go with the speaker manufacturer's recommendations; the ones that gobble up power freely admit it.
It's true that buying more amp than you need is a waste. On the other hand, I might use the top 200W of my amps once a month, but when I want 'em, I want 'em.