I believe however, that the games would benefit MUCH more if devs would simply take a few more weeks to add that content into the main game before its released in the first place.
By the way ... this specifically ... you have to release a game eventually of course.
The industry standard these days however, the average seems to be around 20-25 base CG.
With those exceeding that being the stand-outs rather than the rule.
Anyway ... any author that pushes out their game with 'only' 20 or less could be told they needed more time in the oven.
But if a game was accepted by the fanbase/customers & purchased/sold when it got released. And 2 yrs later they pop out a spin-off game or an add-on to that same game or something, you can't really make that remark stick.
It's the same discussion as DLC in the AAA games marketspace. But the same applies of course ... take story DLC for example, and let's use Borderlands as I'm familiar with those (and they're generally an example of it done right).
No doubt they had their scripts done before they finished & put out the main game. But if you then say that each of those DLC packs shoulda been in the main game, it's the same as saying the main game ought to have been delayed for a year and Gearbox woulda lost a bunch of money on it, which they likely wouldn't have wanted to spend.
And as for customers, the many story DLC packs we got were generally acceptable content for what we paid for it.
-> Basically ... you have to consider your game 'complete' at some point.
In contrast ... Tiny Tina's DLC packs are a total and utter rip off. Though the game itself was rather good.
(We've got other examples of it being done right too of course, like the Witcher 3 or Fallout 4 had some good stuff added later.)