I would love them to be playable. I love the interaction between pet and sim in sims 3. If you want to control them, you can, if not, you don't have to do that either so I think having them playable will be good for all.
Although I am not playing sims 4 at this time, I have bought everything that was put out and will continue to do so until one of my favourite packs is released, then I will play without limits.
I still have sims4 installed with all the packs and updates but still find it boring and haven't played in quite a long time. I am waiting for future EPs to see if it improves or not, otherwise it will continue to be the Sims3 until something of real interest comes along.
Sorry to hear about your cousin. Cancer is a terrible thing. I give monthly to camp quality that helps kids with cancer to enjoy some time on camps for them.