I hate it when someone says your posts are too short. Just because I don't put in filler text about how my OC is uncomfortable in their new underwear, doesn't mean I'm lazy and not adding anything. Ruined my bloody mood with that stupid comment...
I sometimes write long posts, I won't lie, but I do it only when I have a lot to say. If I don't have much to say then there is no need to type some random nonsense to look "smart".