While I agree that more sequels could hurt NMH, I disagree with a few of your points:
The MGS series jumped the shark with MGS2 and despite flashes of brillance it has never recovered.
There are 4 'real' MGS games. The first which is of course 'allowed'. The second you argue "jumps the shark" but only ever in terms of plot, the gameplay is solid. MGS3 was a fantastic game with a brilliant plot (not everyone liked the gameplay but it was done well and was at least different from other MGS games), and I can't comment on MGS4 but a lot of people seemed to like it. So my point is that MGS2 didn't jump the shark, partly because MGS4 makes sense of everything in MGS2, and that by flashes of brilliance you are referring to MGS3 and 4 which were both great games, and both the entirety
of the rest of the series, so your comment about Hideo Kojima ruining MGS with sequels doesn't hold. If you don't like MGS2 then fair enough but as far as I'm concerned the series recovered instantly with MGS3 being great, and then continued with MGS4. At worst, you can argue that there was a small dip in how good the series was during MGS2.
Besides isn't the whole appeal of games like Killer 7 and No More Heroes is that they aren't like other games available.
Not true, these games stand up on the strength of their gameplay, the uniqueness is incidental. If Killer7 and NMH are truly good games, they should be able to be recognised as such even with lots of copycat or similar games on the market, much like God of War is renowned as the best hack and slash in a market full of clones.
Sure NMH2 is a straight sequel but it was a unique case, of him wanting to help Marvelous out after they backed him.
Do you have quotes supporting this? I was under the impression he loved making the game, wanted to make a sequel, but wasn't sure if people would buy it. Then again I might have completely made that up in my own head, so I can't support what I say. Can you?
Whilst I've yet to play it, some of the US reviews suggest the decision to respond to some fan feedback and remove features some didn't like has meant it has lost some of its charm. Which just goes to show how you can listen to one set of fans but end up doing things that another set don't agree with...
But if they'd ignored those fans they would have been upset. Either way not everyone can get what they want, that's just how things are, so it doesn't make sense to complain about that. People like different things, so whether or not Suda51 had listened to the fans, the outcome would be the same.
There is no responsibility to the fans
This argument really quite annoys me, if only because it suggests game developers should be inconsiderate jerks, only interested in creating their own vision, having contempt for those who like their work, and anger at those who don't. People like Suda51, the smaller but more recognised developers, often seem to be the nicest people, interested in making cool games for others to play. Interviewers frequently are amazed at how nice they are and all the cool things they'll do for the interviewer. I of course can't speak this for sure but as far as I know, Suda51 is a genuinely nice guy who makes games so people can enjoy them. If he can get feedback from them on how he can do a better job, or what they like and don't like, everyone wins. In a world where no creator has responsibility to their fans, there is a huge risk of the creator in question making steadily worse and worse games, because they are out of touch with what people want and enjoy, and that's what a game is about: enjoying yourself.
One of the things that bugs me about the industry as a whole is the way they assume if people buy games they want more of the same, that if you buy a game presumably you'd want a sequel.
This doesn't make sense...you're suggesting that if a company makes something that people will buy, they shouldn't make more of it? That's terrible business sense. Sure it's not going to make for great innovation but making more of the kind of games people like and play is safe. The huge companies do this because they know it gets them the most money, and small developers like GHM, who've been going off slim sales from nifty and unique games, maybe it's nice for them to have a bit of breathing space fiscally with a franchise, something they know people will love if they make more of it, and which will get them more money overall.
I couldn't care less about brands, fan service and canon storylines etc.
If this is the case then you are not Human. Psychological research has shown that brands play a huge part in our decision on anything, much more than we personally think they do, and we are
as gullible as everyone else, you aren't special in this regard. Take Contact. That was a great game, but why did I buy it? Because it has the names Suda51, GHM, and Rising Star on the box. Why did I buy the MGS games that I have? Because everyone said they were really good. It is not just me, and it is also you, no matter how resistant you think you are to public opinion. As far as fan service goes, I love fan service! Forget the anime-related connotations and think for a minute. Protoman in megaman 9 and 10? He doesn't need to be there, he's fan service. Playing as Curly Brace in Cave Story Wiiware? That's fan service. Metroid Fusion's suit in Metroid Prime? That's fan service. Fan service can be bad and mess up a well made thing, but it can also be a great thing that adds to the game's appeal and experience. Don't dismiss fan service just because you think you're "better" than people who actually like the game and know what would have made them enjoy it more. As far as canon storylines go, I don't actually have any idea what you're talking about, but I'd love to hear.
Also it's "Do not want", not "Don't want".