Yeah that definitely happens too, and a lot of people call them out for it. Halo is definitely going downhill (not too big a fan of it), Sony is still trying to get some new games, and Ubisoft/EA are very much guilty for releasing games that are pretty much reskins. But when Nintendo does the same thing, very few people complain about it.
		
		
	 
I think it's mostly because whilst the Zelda and Mario games (for example) keep getting more sequels, each one is different enough from the last that it probably could be its own game entirely if they put in a new protagonist, whilst a lot of other developers pretty much 
do release the exact same game over and over with tiny insignificant changes. It's kind of like a lot of other developers are hiding the fact that all their games are the same by just changing the protagonist and settings, whilst Nintendo keep the environments and settings the same but changes the games.
I guess it could be like three different guys trying to sell you a new mug.
- You: "What's the difference between your mug and the one I already have?"
- Dev 1: "This one is red"
- Dev 2: "This one is blue"
- Nintendo: "This one looks exactly like the mug you already have"
- You: "So why would I buy it?"
- Nintendo: "because it has a built in straw, four handles and makes all your drinks taste like strawberry milkshake"
Basically, just because Nintendo use the same characters across certain games, doesn't necessarily mean it's the same game...Likewise, just because a game has a new protagonist doesn't necessarily mean it's an entirely new game.
Not to mention the amount of time between releases. You get like one game per series with each console, two if Nintendo are feeling particularly raunchy and rebellious at the time. Add that to how significantly most of their games change and there's even less room to complain.
CoD and Assassins Creed on the other hand get a sequel every year with little changed. It won't surprise me if they start releasing two games a year.
I agree with Halo though. I used to love Halo. It's the entire reason I owned an original Xbox and a 360...They should let the series die though. Halo 4 was pretty shoddy, Halo CE Anniversary was pretty buggy and broken and from what I've heard, with Master Chief Collection they were too interested in draining peoples wallets than releasing a working game or fixing the broken game.