I think most people think of IV like II because of the "how many of the same game are we going to see?" epidemic. Of course every iteration of II had differences making them discernable, but probably a good number of people are looking more for innovation.
I agree. I'm glad for Street Fighter 3 (I may buy it, if nothing new or underrated is available), because it was something refreshing than the other ones and likewise for King of Fighters Maximum Impact, even though the movement animations should have been better for it's time. However, I do expect innovative game play for recent fighting games like these and others, but it's below satisfactory.
I wish that the audience can be open to something new and not so content on redundancy.