Freelancing in addition to a career
I think it would be really cool if Sims could have a career and also be a freelancer on top of that. In the modern gig economy it’s not uncommon for people with a full time job to also do some freelancing on the side. We’re also already able to add a side hustle to some careers, hold two part time jobs simultaneously, and be a business owner in addition to having a career. I think it would add some realism to the game since many people wear different hats and have multiple income streams going at the same time.
There are several cool things you could do with this gameplay wise. Maybe your software engineer also does some freelance programming on the side. Or, your author or journalist sims could take on proofreading gigs from the writing agency. A sim in the painting career could also make digital art as a freelance artist. Sims can be both an educator and a candlemaker. It would give players some extra ways to customize their sim’s life stories, which is the main goal of the game.
The real reason I want this, however, is because I want my sims to be able to be paranormal investigators without quitting their day jobs. They could be a mild mannered professor by day and spend their night confronting the spiritual realm, all before going back to work the next morning to lecture a bunch of ungrateful students. A mortician can prepare deceased sims for burial during the day and then deal with disembodied spirits by night. It would be so cool! Also, I survived that week in a haunted house, the least you can do is let me monetize my ghost wrangling skills without having to give up the career I already spent so much time on building.