i won't mind if it doesn't come as a world but if they do decided to add a world i think plantsims will be more usefull there (maybe it's because i grew up with The Sims 2) with maybe 4 neighbourhoods and each event based on 1 of these seasons
like maybe you can decorate pumpkin during halloween in the autumn/fall neighbourhood
summer activities in the summer neighbourhood
easter activities in the spring neighbourhood
christmas activities in the winter neighbourhood
(just to name a few of course)
nature stuff that becomes functional you can actually take care of them (The Sims 2 had them) the grasses, the trees, the flowers, the plants and if these are death the plantsims can bring it back to life again
more water activities like some sort of water sport like water competitions
that will be a lot more usefull if it comes with a world
i know there's calendar for it to disable things such as christmas and valentinesday activities but i rather have them in the event similair to San Myshuno, Henford-On-Bagley and a few other worlds
we can always have a party you have a day off from school and work and do packs that complement with Seasons since calendar became a basegame thingy (think about some party like My Wedding Stories, Growing Together and other parties that comes with other packs)
i agree with stuff you've mentioned that isn't designed for other worlds such as like a market you can sell things, that should change
i won't be upset if they won't add seasons as a new world but i think based on my ideas it should come as a new world
i do agree it should come as a refresh/overhaul for better gameplay