Seasons make me feel like there's some progression of time, like years going by or something. Right now there's only really one thing to indicate that, and it's your sims getting older.
I also kind of have the opposite issue from you regarding weather where I live. Image sims 4 weather in real life. I know I should be grateful that I live in a place with mild weather but it gets kind of bland having the same weather day in day out. We hardly even have rain! I have to drive hours for the nearest seasonal snow! Anything other than sun excites me, so if I can't experience it I want my sims to be able to.
I guess seasons just spices up the game for me. It adds more variety and makes it feel more real. I honestly wouldn't mind a season pack (or patch) being mostly aesthetic, with a few added interactions.
