From a business perspective it would make more sense to do world packs in sims 4 than it ever did in sims 3. In sims 3 players could create their own world or edit existing ones. Through cc we could have more worlds without handing over money.
In sims 4 we don't have that luxury. We depend on ea's good will for new worlds. Itis sstrange they haven't exploited that situation yet.
I think in the early years of sims 4 world packs would have been very popular. But at this point with so many worlds in different EP's and GP's I don't feel the need for more worlds anymore. If a world would have a very unique feel, I might be interested.
I think if they ever did world packs, they should be base game compatible. If extra content is required (deco, plants,...) it should be included in the pack.