Well, this is talking about food waste, not pollution. Even if it rots and doesn't do anything, worst case it's a pile of bio-matter. The land, and everything involved in growing them could be used for actual food though, which could decrease food prices potentially.

Still, it's not a big deal and there's bugger fish to fry, but it doesn't mean it shouldn't be considered. Changing your mindset can make other issues and solutions more obvious.

Halloween food - no.

Halloween plastic decorations, wrapping, costumes.... yeah, we can do without

It's low priority for sure.

It certainly can be

Golf courses come to mind

Or cruise ships

Pumpkins are pretty low on my priority list, but entertainment isn't really a good reason to throw useful stuff away. It's a waste of water, waste of growing space, waste of fuel for harvest and transportation, and obviously a waste of food.

Sometimes! I think pumpkins are fairly harmless though

Frequently, yes.