I would rather they have a deeper focus on less things than a superficial focus on a wide variety of things personally. I didn't play Sims 3 past the first game. I looked up let's plays today on the acting career or the film career. There is little to nothing there. What there is revolves around someone usually doing their house, going to a rabbithole career, placing some studio? lot somewhere that they can again rabbithole into?, being famous and gaining more fame from interacting with others. Oh and skilling to advance. I remember hearing I gotta do this often. It was weird to me how few videos were uploaded about it frankly.
I'm sure some might have built grand stories or had grand gameplay around all that but I don't see how I could (I will concede partly because I disliked the game from the start and could never get past that).
What I see coming for acting here in Sims 4 through trailers, what's been said by gurus and some statements from Sims Camp and some assumptions is this...
I can have a sim go into an active acting career lot, have a lively set around them with directors, makeup artists and other jobs I'm not sure of. They can get ready for a scene involving hair and makeup, they can be in multiple scenes with different genres (still waiting to see how that plays out). They have a perk system that someone at sim camp said is like the vampire system. They have a separate fame and reputation system with at least one assurance that they learned lessons from the past by the sim gurus (so to me that means options or at least not overkill still gotta wait on that), they have bodyguards or can, they have fans that look to have multiple reactions and autograph signing, there is a walk of fame and the getting of an award pictured in the trailer (not sure how it works yet but it does look good).
On top of that of course we have a new world, the ability to apply the fame and reputation system widely (but not to be worried about it) learned today you can get famous by giving money away for instance, a money vault that you can play with (gameplay object?), and of course the build buy/CAS that is almost always impressive to me.
I'm sure there is even more...
Either way though if it's this focused I as a storyteller/player am looking forward to this with bells on. It will give me way more stories to tell.