Anyone who hasn't bought into the idea of micros hasn't found any good ones! In urban or suburban areas these caches are priceless. If you think that going 3 miles into the woods to hunt for a 35mm container is painful, how about looking on the side of the road for a tupperware container barely hidden behind a tree? What a waste of time!
Most of my favorite caches have been micros - whether hidden far in the woods or bored into a hole on a telephone pole. Many micros are very clever. The sprinkler head you play soccer above may well be a cache. The power outlet on the side of the building may not actually carry any power - but a cache! It opens your mind to realize that any common object you see every day may not be what it appears to be.
I agree that one of the best aspects of geocaching is that it gets me into the outdoors. When you live in a city, however, getting out for 30 mins at lunchtime is sometimes the best you can do. Not many ammo cans can be hidden at the corner of 18th and 8th, but countless micros can!