is it just a simple demo, i really think they should be doing an open beta to test their netcode and ensure its the best it can be
A netcode-focused beta after the game has gone gold and is in production wouldn't mean as much, though. I guess it could get us day one patches to adjust some settings, but it's not going to totally rebuild or configure the code entirely.
After the final game code reaches the wild and gets real stress, we'll see how they go from there. I'd love for them to totally blow away our expectations, and end up with something Killer Instinct like (which normally feels better for me than anything else released on console.)
The point of a demo now, I'd wager, is to get the "playing is believing" crowd on board. Let people know it feels like a KOF, and see all those details people claim YouTube totally destroys VS seeing it with your own eyes.
It'd be great if their next fighter could have a beta that's as updated as trailers have been for this game; imagine getting new network code, characters, or stages to play around with on a weekly ~ monthly basis.