I'm sure many people would attend more if there was a reason to. But at the end the possession bonus is only cosmetic, I also don't care about supporters. The only thing is you get a green for making a sub and a blue pack more. And I'm very happy with my results when I not attend, whereas I had more negative experience when attending. I think the game just makes the decisions for you and they make you believe you have control.
Just my personal opinion though, I'm sure other people will say different things. I play for too long to believe in the game mechanics anymore.