It's a love/hate thing for me...
While I don't hate seeing seasonal merchandise early, as much as I do inapropriately early seasonal MUSIC (ARRRRGH!) it bothers me too, for all the above stated reasons.
However, I'll bet that most of us have at least one seasonal favorite that's not on the candy rack the rest of the year. That makes it kind of hard for me to completely condemn the practice.
My main weakness? Holiday Reese's Peanut Butter "cups". I don't know if it's the size, or freshness, but the individually wrapped Easter Eggs, Pumpkins, and Christmas trees are way better than the regular cups for some reason. My best guess would be freshness, since the seasonal runs are pretty much garanteed to only be so old...
There's few things more dissapointing than a Reese's Peanut Butter Cup when you open it up, to only find all the grease from the peanut butter has leached into the bottom layer of chocolate, leaving the peanut butter like a poor imitation of sawdust.