I shoot in two environments that have a lot of crap in the air, the ocean and the desert. I have had salt air fog my filter in a matter of minutes and last weekend, off road vehicles raised huge amounts of dust that I couldn't see through. Trying to clean a lens in the field is much harder than wiping off a filter.
That has always been my consideration, too. In most circumstances where I've been working outdoors, things happen quickly and cleaning a "disposable" filter with a shirt-tail or whatever else works, is much more desirable than rubbing away on a coated and expensive optic.
