Some of the released content is nice, but a lot of it is very poor when compared to previous games. I really like the way magic and vampires have been handled in the sims 4, due to the addition of proper skill trees, rather than just a skill bar. Get famous also adds a cool fame tree that allows you to unlock perks for your sims, a shame the rest of the pack is slightly underwhelming. Apparently parenthood is a good pack to have if you're into having large sim families, but that's not really my thing. Pets is a HUGE downgrade from 3, getting rid of horses was a mistake and I hate how you can't control the pets. Most of the stuff packs should be avoided, due to the fact that fan made custom content is usually far superior to whatever EA themselves create, but I think Vintage glamour and Laundry day add in some nice little game play features which make them a little more worthwhile. My biggest issue with the sims 4 in general is how small the neighbour hoods are and how the areas around you are glorified back drops, near enough everything requires a loading screen. City living is the worst for this as you need a loading screen to visit your neighbour that lives 4ft away from your front door! Had they made packs that helped eliminate these disastrous issues I would have definitely recommended those, but in many ways some of them make it worse.
Maybe check out some youtube videos for fan made mods, the mods for the sims 4 are next level crazy (good). You might find what you're looking for there. Like you and a few others have said, I would happily pay $15 a month for access to all the expansions, but there's not a chance in HELL I would ever consider buying everything for $400 in one blow, it's just not worth it.
PS - Avoid the pack called dining out at all costs. It's a glitchy mess that only sometimes decides it's going to work as intended. It needed a lot more refinement before release, but unfortunately a lot of the bugs/glitches have never been fixed. (Also something as simple as going to a restaurant with your family for a meal should be included in the base game, UNLESS it comes with a tonne of other features i.e. previous dining out styled expansions.