It depends on the game. Japanese devs are notorious for adding new content in NG+ runs. A good example is Armored Core 6 where you can still get new content up to NG++ and the one that takes this to an extreme is Nier Automata where the meat of the game is the NG+ runs.
Exactly. NG+ doesn’t add any content, it just gives you an alternate way to explore the content you missed.
I’d pay for an expansion, online access, and maybe additional characters (i.e. different play style in existing content), but not NG+.
It depends on the game. Japanese devs are notorious for adding new content in NG+ runs. A good example is Armored Core 6 where you can still get new content up to NG++ and the one that takes this to an extreme is Nier Automata where the meat of the game is the NG+ runs.
Thats not really NG+ then, thats just the base game.