I totally agree, but that is locking the stable door after the horse has bolted. I don't know all the ins and outs, but what is to stop Sephiroth using them again? Or manipulating Genesis to the same end? (If someone who has been paying attention to the finer plot points can explain this, please do)
There's just simply not enough Jenova left for him to have any sway over. Great Gospel got rid of any in the vicinity of Edge which included the single greatest collection of them remaining (her head). They may be scattered elsewhere in the world but she's been pretty summarily pulverized. And the end of Crisis Core implies that Genesis doesn't have any anymore either, otherwise he'd still be decaying.
Furthermore, Case of Lifestream Black outlined just how much effort and sacrifice it took for Sephiroth to maintain cohesion in the Lifestream the last time. I doubt he could do it again. Cryptic messages notwithstanding.
In storytelling generally yes, but I'm basing everything on what has occurred in the compilation thus far. I'm sad to say that I don't trust them to create new characters with some sort of integrity
I'm not totally sure what you mean by integrity in this case, but they have already invented new characters. Genesis and Angeal aren't very popular. But I don't hear too much abject hatred for the Tsviets themselves. People seem curious about what Weiss is REALLY like. There are any number of things they could do with Argento. Shalua as a character (if not her design) was perfectly fine (then they killed her, but I mean as an example). Nothing's wrong with Denzel himself, or Shelke. I don't see the problem.
All that 'I will never be a memory' crap, and how hes somehow linked in with Clouds mind tank. And the fact that SE wouldn't put out a game without him because he's a money spinner apparently.
He wasn't in Dirge...
And I have ALWAYS thought that line meant that he will always be more than a memory to Cloud. He'll always be an absolutely colossal part of what shaped him as a person no matter how much he tries to forget it.