Interesting points - but, I think, you can apply it in many other places other than games. Films, TV, literature etc can suffer just the same. The original spirit is gone... unless you're incredibly skilful, and moreover put the sequel out quite quickly, you're probably going to fail.
Series that are actually planned as series? That works fine. But arguably the second one in that chain isn't a sequel as such. It's just "part 2".
Having just put some recommendations of their stuff in another thread, I think this may be why Studio Ghibli films work well. It's a bit of the Silent Hill effect, even. You can recognise similar traits and styles in the characters that are presented (given that the lead artist seems to know how to draw about eight or nine different faces and bodies very well, and doesn't bother doing anything except mix and match them), and in the theme (strong feminist, pro-ecology and flight elements abound), but they are always actually all-new characters in an all-new setting with a whole new story. They have no real, typical sequels in their catalogue - no dreadful Disney-style "Pom Poko 2" or whatever - and each story is presented as a self contained whole. The closest they ever got was The Cat Returns ... that took a statuette that featured in the creative daydreams of a character from a film 10 years previous, made the daydream character of that statue real, and brought it into this world. With basically every other thing having been changed, including the location and all of the humans.
They continue on almost perpetually strapped for cash, and always leaving the punter guessing and hungry for more, but very well regarded amongst their peers and their audience. If that isn't a pointer to the true nature of the sequel and of the remake (lazy cash-ins!), what is?
...that said, I did end up seeing The Fast and The Furious 5 recently because of a ticketing mix up. The way the story seems to have flip flopped, been retconned, "finished", then picked apart and continued along the way since the last one I saw (think I dozed through about half of F+TF2?) seems flat out amazing. It was a perfectly enjoyable film, but you had to totally ignore the plot and just treat it as audiovisual candy... hehehe that was a funny joke/bit of slapstick, wowww that was an amazing stunt, etc. Sort of like a casual game, or something like Trackmania. They have now put a lid on it by having everyone retire in paradise off of their arguably ill-gotten gains, but would you bet against some plane full of true villains crash-landing on their island for F+TF6?
The one thing that subverts all this is Doctor Who, which has a false end to everything ever / the main character being killed off about twice a series (and, in fact, this series pretty much opened with the latter in the most final of ways)... but its become such a cliche of the programme that it's pretty much expected now.
Perhaps Moffat should confound the audience - and risk having them hate him forever, with a gamble that by giving them something they didn't even know they wanted, they'll actually love it - by making him permanently dead forever and ever, bagsy no tag-backs, about halfway through the series, leaving the companions to try and muddle through the best they can?
