Yeah, I'd agree with that, I wasn't really trying to put the "out with the old, in with the new" point as the crux of my argument, it was more of a related point. But it's more the case that I don't really think there's a need to constantly extend older series to modernize them. Remakes, for instance, offer a lot in the way of freedom in terms of design in moderation. Some take the orthodox route and just improve the graphics and tighten controls/features (ie Ocarina of Time 3D/Majora's Mask 3D) while others go all out and change aspects of the story, gameplay, characters, and the like (ie Hyperdimension Neptunia Re;birth). Similarly, I don't think there's anything wrong with revival entries either, ones meant to revive old series or completely restart them- since I don't think they have to stay dead.
My only real point here is that I don't think we should keep asking for more and more sequels to series or, if they do, expecting the same or a similar experience as they've been receiving if they do get them. I'm not trying to say that something like Metal Gear has been here too long to keep on going, but when a series has an ending- a point where it can stop and leave the player satisfied, I don't really see any reason to push it- and I guess "push" is kind of the idea here. With Metal Gear Solid 5, that wasn't something that was called for because of massive outcry, that was a Kojima development (or possibly a Konami one, for financial reasons). With something like that, I don't really see any reason to worry. But with something like Megaman, where Keiji Inafune has left the company, pretty much anything Capcom does with the series comes under scrutiny, and people still ask for more...you're really playing a dangerous game.
And I'm not saying that series need to die, but when I see series that have recently come to an end and lived something of a full life (which the length of, I'd say, varies from series to series) and then people ask for more, I often have to wonder if they got anything out of the experience at all. It really seems to be the difference between potato chips and an expensive steak from a high class restaurant, where in the case of the latter you just eat and you eat, and at the end you want more. There's not so much a sense of fulfillment as there is the enjoyment of eating it in the moment, while in the case of the steak you enjoy it and, once it's gone, you're sad (so to speak), but you're glad you had it and the experience left you satisfied.
Or, I guess a more relatable way to put it is the difference between Call of Duty and Chrono Trigger, because it's the same way really. But in the end, I guess it's better for me to say that I don't think that we should constantly ask for companies to shell out more and more from series that have lived full lives rather than that they should pass on. Having said all of this, I can't well say that there's anything wrong with wanting more out of a series you love or a company responding to demand, as there is always potential for a series to go on and still feel fresh. It's just that, if pushed to a certain extent, it can become unhealthy for a series (especially in the case of something like Megaman or any series that is samey throughout several entries).
Remakes don't encourage creativity and progression in quite the same way a brand new title does, though. When you're remaking a title, you're bound by certain conventions: you can update the gameplay and add aspects to the story, yes, but you're still essentially re-relasing content several years old. It might still be good, but it isn't a fresh idea, so I think a continuation of a series is needed every now and then, so that developers can experiment with all-new ideas, rather than covering the same ground again and again, just in a slightly different fashion. I realize you can argue that they do that with sequels and such anyway, but the option not to is always there.
I think a reboot would actually be a better way to go, though - it's a great compromise in that it gives people more of the series that they love, and lets developers modernize the series and take it in a completely new direction. Plus the reboots I've played in recent years (Castlevania: Lords of Shadow springs to mind here) have been fantastic; sometimes it's exactly what is needed.
Oh, I'd agree with you...the misplaced sense of entitlement fans have of series these days is ridiculous; just because a game is slightly different to its predecessor or expectations does not mean it should be shunned, or dismissed, and so on. These things shouldn't be pushed, but at the same time, just because they have a definitive ending to a story doesn't mean that they have to come to an end...prequels, alternate stories, or sequels from different perspectives should always be possible. Pushing a story that's got a definitive ending is bad, I'd agree, but I would say that the series shouldn't be bound by a single story thread - the world is bigger (or should be bigger) than a single character. In the case of Metal Gear Solid, something like Metal Gear Rising is a great way to carry things on.
But I think, regardless of who develops a game in a series, there is going to be scrutiny; it's inevitable when a series is popular. Look at the debacles surrounding FFXIII, DmC: Devil May Cry, Resident Evil 5/6, The Legend of Zelda: The Wind Waker...the list is endless. Once a title hits it big, everything that follows it is compared to it, and if things don't measure up to ephemeral, often unrealistic and wholly unreasonable vocal majority expectations, there is hell to pay, regardless of how good or bad the title actually is. I don't think Metal Gear Solid should be tied to Kojima because, whilst he might have started the series off and made it what it is, that doesn't necessarily mean he's the only person who can carry it on, and scrutiny will come regardless of who does it. The same would apply to any other title. As long as the idea is solid, I don't think it necessarily needs to come to an end. Of course, if the idea isn't solid then that's another matter entirely, but just because one person can't do it doesn't mean that there isn't someone else out there who is equally competent, if not more so.
I guess it's because people get so much out of a series that they want more of it - the phrase "too much of a good thing" doesn't really seem to apply to video games for a lot of people, because things remain fun. I mean, I buy and will continue to buy a lot of series, because I doubt I'll ever get bored of them, and I love the little things that are changed or added in each instalment to make them feel fresh. I think it depends on the frequency and the nature of the titles, really. As you say...the difference between Call of Duty and Chrono Trigger.