Is there a "official" complaint system to express the frustration of the number of wag bags on the trail? I'm not asking about the process to implement a new waste disposal system.
I can't answer your question directly, but would offer this -
As I was descending Whitney a couple of weeks ago I met a backcountry ranger a bit above Mirror Lake as he was ascending. After checking my permit, we visited for awhile, and I mentioned there were lots of WAG bags up higher, including at least one within a foot or two of the small pond at Trail Camp where many obtain water. We both agreed that while the number of hikers over the past 5 years or so seemed relatively static, there seemed to be a noticeable increase in the number of WAG bags left behind. He commented there seemed little the rangers could do about the problem, other than make an effort to pack them out