I do end up with some food left in my zip bags which I have to carry out. On a six day resupply schedule it sometimes builds to a pound before I can dump it. However, I have never been bothered by it becoming noticably smelly even in August. Of course, that may be because I have and just don't notice it!
For me, the trade off of having to carry the extra trash weight is well worth it - especially on short trips. I can spend more time doing what I came to do (see what's over the next ridge, lean against a tree and just enjoy being), spend almost no time "in the kitchen," and still eat heavy.
About 52% of backpacking trips are less than 100 miles according to a recent survey I read. For those hikes, resupply probably isn't an issue. On longer trips, instead of trying to shop for food along the way, an option many use is to mail themselves a resupply box. It is almost too easy to just transfer the new prepackaged meals, film, fuel, etc. to your pack, and head for the AYCE buffet!
Civilized life presents enough complications. My mantra on the trail is, "Easy is good."