Because it would likely do me more good airing my gripe to them than to my congressman, who is a worthless liar who cares for nothing but getting re-elected at this point... I've lodged my complaint with Dish, with Tribune (twice) and the local FOX affiliate (KCPQ) and so far nothing's come of doing that (except a reply from KCPQ saying, essentially, "sorry, but there's nothing we can do"). So I'd likely be wasting my time/effort with the FCC too, but at least I might feel better...
In the past the FCC has been known to occasionally listen to consumer complaints. Maybe if they got enough of them...