Well, when I got the base game and saw the launcher, which I love, I saw so much potential and I really wished they'd maximized on it. It means the end to expansion packs! Not that they wouldn't have them; I suspect that my idea would promote content production by a lot by providing instant customer feedback and rewards.
The idea would be like the stuff on the exchange, except it wouldn't be "objects", it'd be things like "Temperature". So for $2.50 they'd sell temperature, or for $10, you can get temperature and related paraphernalia and things, while for $20 they'd sell the seasons as well and stuff. I made up numbers, but it'd be that kind of thing. So you would download it directly from the launcher and never have to buy an expansion pack- you could even buy parts of expansion packs. (example- If you really liked China but were not interested at all with Egypt, you'd just buy China) This could, indeed, get complicated, but I think they could work it out.
In a specific mention, I'd like to say that I'd like to see something that's very different than what one would expect- I want to see injuries. I know that's weird, but my first character in the base game was Dr. House, who has a limp. I couldn't put in the limp and I was disappointed. I don't think injuries have that great a marketing value, but if they implemented the system that I outlined in the first part, I feel like things like injuries and disabilities would become more of a feasible thing.