I think, and this is just my take on it, how good Sims 4 is for storytelling depends on how much "heavy lifting" you want to do yourself vs. how much you want the game to do.
I, personally, find that I enjoy saves the most when I start with a rough story plan. For example, the founder of my Seven Stories legacy:
"This is Ashley. Her family home burned down while she was taking her little brother to the park, so she's had to give up her plans for going to Uni to make enough money to rebuild the house again and provide for her brother to have the chance she didn't."
Yes, it's just a basic Rags to Riches game, but there's a story behind it, and an end goal (rebuild the house, send the brother to Uni). Do I wish that Sims 4 would throw a few more curve balls than it does? Sometimes. But those aren't needed for me to tell a story and enjoy the story I'm telling myself.
Right now I'm raising Ashley's Great Granddaughter and preparing to kill her father off in the temples of Selvadorada over winter break in preparation to run a Quest based story with her when she gets to Young Adult. Angsty backstory incoming!