Shivering Isles is exactly what DLC should be, it's an excelent example. And horse armor kinda as well depending on how you look at it. It was a dumb feature that clearly wasn't meant to be part of the game and it's essentially cosmetic since there's no mounted combat nor is your horse supposed to tank damage. Considering what they gave you, it was pretty cheap as well. Although, it was mostly a bad joke by them, so…
That's stupid. That's essentially what pre-order bonus are or day-one DLC or even Season Passes and I don't think you'd be defending those.
If someone makes Game A and says he'll be selling it for 20$ and you agree to it, whether there's DLC B, C and D for 5$ each has no bearing on it since you'd still have to pay for it afterwards. If the game looks complete when you decide to pay the 20$, it doesn't become "incomplete" when they show even more content, that's just too stupid.
Anyone that falls for that shit is an idiot since it's that kind of "buyer's remorse" that marketing exploits and that feeling of "missing out" is engineered by them so you end up paying 35$ instead of only 20$.
If you're that kind of retard, refrain from buying videogames at launch and wait for the GOTY edition or just buy the game and pirate the extra content.
The content is still there then. All's well in legal terms.
The reveal of a prebuilt, pre-rendered video that was likely not even the final version? That's not gonna stand in court.
You keep mentioning performance issues but that's not what it seemed you were mentioning. If Witcher 3 did not had Ciri after she appears in every marketing material or if you didn't got a sword that was promised with a pre-order, that's one thing. That exactly one piece of advertized content not being delivered.
Performance issues are not the same thing since companies can defend themselves with "alpha builds" or "works on my machine!", it's really not the same thing.
You want more pizza analogies, it's like asking for a meat pizza and when it comes it doesn't look at all like the catalogue, but it still has meat so shut up?
Stop. The clients made it acceptable, not the market. Put the blame where it belongs.
And last I checked, Capcom got a lot of flack for that shit, as did Bungie for Destiny. I really have no idea where you got the idea this is "acceptable".
What? No, it's not like that at all. Shivering Isles for instance is never mentioned or talked about during the whole game and neither is any expansion in any Bethesda game, for instance or even Borderlands. Each DLC pack is it's own thing separate from the main game.
There are a few specific examples like Destiny where they left cliff-hangers for the DLC but they got a lot of flak for that shit and Destiny 2 will pay the price for that shit.