I think there are a lot more important things than H2H. It has been my experience of other H2H games that people are more interested in using AI exploits and rediculous playcalling than actually trying to play a game that resembles football. Also, when H2H is available, people tend to like the anonomity of the internet and bail as soon as things don't go their way. "I'm down 10-0 halfway through the first quarter, I'll just drop and find a new opponent" is the way most people (especially those 25 and under) think about H2H.
I think an improved game engine/physics, the ability to create zone schemes other than cover 3, and improved roster management (split DL into DE & DT, secondary into safeties and corners, possibly LBs into inside and outside) are more important than H2H. I don't think you can have good H2H until you have a good 1P game.
Also, with H2H, you are catering to a percentage of people, whereas general game improvement helps everyone. The needs of the many outweigh the needs of the few (unless you are a polititian, then the needs for money is greater than the needs of you ).