I really like the ideas you mentioned and think all three should be bundled into one pack as they are all connected. Like you said, I found it a bit irritating that illness seemed to be random and it came and went so that a child sim was feeling sick at school when they cannot take medicine but fine at home. If you give them medicine when they get home, they get drugged/dazed. I was disappointed that you could not take your sim to see a doctor or visit the hospital.
I especially like the enhanced sports options. I am very disappointed that there are really only soccer and basketball as options for sims to play on their own. And what happened to sports at university? I think it would be good to include a wide variety of sports, including those popular outside of the US so it is more inclusive (rugby, cricket, etc).
I bought Sims 4 when it first came out, played for 5 hours and then did not play again until a couple of months ago. I stuck with Sims 3 as I found it to be more satisfying to play. When I started playing Sims 4 recently, I thought maybe I had not given it a fair shot and hoped that with the various expansion and game packs that I would feel better about it. There are definitely some areas I am really enjoying (dolphins and crafting in eco), but I do feel the loss of the depth that Sims 3 had. The other issue with all of our ideas being wrapped up into a launch of a Sims 5 rather than improving Sims 4 is that this seems to be a cycle. They advance a franchise and then launch a new one that is very basic and we have to play and debug and pay for more additions to get it to where we enjoy playing, and then boom, another franchise is launched. I realize that Maxis/EA needs to make money but after my disappointment in Sims 4, I am not sure I would buy any future franchise launches. Expansion packs yes, but a new franchise, no. I have been playing Sims since right before Sims 2 launched and it really is my escape. It would be nice if they would dedicate themselves to a franchise to make it great rather than keep rolling out so-so franchises after so many years.