Zone of the Enders never really caught on the masses for good reason. At the time the developers’ aim was to make high speed japanimation robot action game. That they did, and thus hit well into certain crowd. Z.O.E series has got a lot of attention after their release, and never really god bad reviews or anything. Both games were cult hits, and being a cult hit isn’t a bad thing, but you need to take advantage of your cult status to make the jump to the masses’ living rooms. KONAMI never did this, and while Z.O.E did get a GBA prequel and two animations, one direct-to-video, and another as a TV series, it wasn’t big enough to greenlight the third game.
Do we need a third game? Fans think so, and Hideo Kojima wants to make one, so I’m in. The story of the first two games has been finished, so the third game will most likely have nothing to do with them. That, and they have said that they’ll create another theme with it. The fans want fast paced robot anime action, and they’re only going for the fast paced action. We’ll just have to see what comes.
In the meantime, we can always kill time with the original two games, with or without HD.