I have played vanilla since the beginning, honestly. Since Sims 1 days. Modding has come a long way, but especially with the first three entries I never really needed it. If I wanted to skip the grind, all you have to do is cheat, and back then you had more control over the worlds culminating in 3's CAW.
As for 4, for a long time I looked over its dullness as the new game with not enough packs and patches. By the time I stopped, I came to the conclusion that it would take an egregious amount of mods to fix my specifc qualms and that I did not have the patience to find nor manage them.
I have used mods for other games, but I specifically avoid it with ones that update often. Mods seem like more trouble than they are worth to me, since I think I would have to jump into the deep end, and I usually do not like the look of CC. I like the styles to match, but even in the cases it can I feel no desire to chase down more CAS and BB. After so many packs, and still more coming, I am good beyond new gameplay objects. For me to really consider it, it would have to be Steam Workshop level easy.
As for how to have fun, I can honestly say that my playstyle has had to change drastically to accommodate 4's strengths. It really does have a good CAS, CAP, and BB. I do a lot more tweaking and saving there for my favorite Sims and builds. I used to create a family, a family house, and then play in live mode the entire time. My play time is not nearly so linear anymore and I hop around a lot. Live mode just doesn't hold my attention as much.
I also nearly exclusively play with eight sims because one cannot hold my attention. Pets, my favorite in every other iteration, feel like walking decor so I don't really play with them anymore. Beyond that, I reroll characters I like a lot. I replay stories with my favorite families that I spent so long tweaking in CAS. My long term saves are few and far between, but back when my playstyle was still changing I did have a Newcrest centered file that entertained me between two to three years. I wish I could get that back, but I still have fun. Just small doses. I cannot play hours at a time like I used to unless new content just dropped. So, it is all very episodic for me.
I hope that answers some of your questions. Summary: mods and CC are too much trouble for my taste so my usual playstyle had to change a lot to accommodate 4's strengths.
