It would be nice to add cooperative playthrough, so you can dive into the world of Cyberpunk with your chumba.

Choomba or choombatta. Definitely.

"Worst thing" is, it shouldn't even be that hard to implement, given the recent cross-save function. With both players using the same game version - obviously with mods, if installed on either player profile - it shouldn't be that hard for 2 players to load their own character into the same game.

It could have certain restrictions over the internet, but on a LAN game, I don't see what the problem would be. Maybe even skip out on network features by using UDP for less stutter, just like good ol' StarCraft for LAN gaming.

Given the data intensity of Cyberpunk 2077, I think LAN exclusivity would be best to avoid stuttering on lower-end connections.
I would love to try my 10 GbE home network and TP-Link TL-SX1008 switch for gaming sometime. ^^

No. How about you wait first if they manage to make more balanced single player with the expansion patch before wanting more.

For a truly balanced experience, I would demand a complete physics and NPC AI rebuild.
And I know that won't happen now, it's way too late.

So, nothing wrong with wanting more features, when in the knowledge that what is still wrong with the game won't be fixed. :)

Personally, I think they should have skipped Playstation 4 and xBox whatever compatibility, and instead spent time setting the game up for PCs that are actually made for running the game the way it's meant to.