There is a clear line - those who like it and those who hate it.
Those are against it repeatably state a glaring flaw - the latency in fighting games. While I do agree that execution can be critical in high-level matches, some critics go as far as saying that it completely changes the game.

While I am not going to argue with those two critical points, I do believe that all fighting games from here on out should have online play. If you are in the United States or Canada, you'll notice that arcades are far and few between these days. Even if there is an arcade around, there is no guarantee that the local arcade will even get the newest game just for the sake of a few people. By the way, a 4 cabinet setup in an arcade will cost them $70k! SEVENTY THOUSAND! Wow. Just wow...
So what else is there? Consoles and online play. Like it or not, online play is here to stay. We've come a long way, and service keeps improving. Not enough for some of the critics around. Online play allows one to play games in the comfort of their own home. For those who don't like it? Don't play online. Have a getogether. Go find an arcade that does have it. But don't spoil it for others who simply want to play other people.
Anyhoos, this geared more towards Sega. HAVE ONLINE PLAY! Namco is coming out with an online version of Tekken 5; Soul Calibur 4 will have it, SF Turbo HD Remix will have it... Why do you hate us, Sega?!?!?!?