I don't mean the really cool DLC's that were fleshed out linear mini-campaigns that required voice actors & writers (although those too would sell).
I mean stuff like The Tower, the first-person tower defense mode that had crates you could fall back to to heal but if you did there were spawners for future waves to come out of the enemies could unlock to make your current run harder to manage.
I also mean stuff like the one Heavy Strooper DLC, the one where you're just an massively armored guy with huge guns on the frontlines of an all-out war the scale of which is never depicted in the actual campaigns, even though you basically never move from the spot ur standing on.

Basically if a mod-maker got hired by whoever had the rights to the game to make stuff like those with almost any amount of polish, I would 1,000,000% buy them lol

Heck, multiplayer integration for a pazaak-only mode you don't need to load into the actual game for would be an easy buy.