I don't see why having a raidiant-like mission system is a terrible idea for this game.
* It allows you to continue to explore and enjoy the massive world that was created.
* The world feels more alive
* Opportunity to increase funds for frivolous things such as car collecting, respec, etc.
Also, when I completed my first play-through just recently, (I bought/played after 1.3.1), once I completed the main quest, I never had an option to return back to the game to enjoy the new items I collected while finishing the game. And even IF I had been able to go back, there would be practically no reason to use them as I had completed just about every side quest given.
Night City is a huge, beautiful map. Offering incentives to continue playing offers longevity, and more so with mods that can be added if that's your thing. I do not use mods in 'this' game, but with a radiant system, I also have seen the benefit in similar Open World Games that have allowed buyers to endlessly enjoy the world that was created.