I'm not too fussed on it having its own world, as I think that would take a lot of what we love about the pack away. But I do agree with you on there needing to be an update. Adding more CAS clothing would be nice, like a wider selection of coats, scarves, better hats, and better gloves! They could even add a variety of leg and arm warmers. Can they please give us better and more umbrella options!
I'd also like to see more seasonal interaction, so our Sims can have proper discussions about events, etc. The preferences that Sims are able to chat about get boring quickly. Like snowball fights, or having parents teach toddlers how to make snow angels. Overall, I do think the pack is lacking now and needs a big update to make it better for us to play.