I think it's daft to stand up when you pay for and are supplied with a perfectly serviceable seat. Makes as much sense as going to a restaurant and standing to eat your meal.I've been sitting here in the local thinking about this question (I must get a life) for ten minutes and still don't understand it. Do I stand when driving my car? Er no - coz that would be extremely difficult as well as stupid. Do I stand when I go to watch football? Yes - coz it's not the the local Odeon.
My point is that you can support the team just as well from a seated position.
I have no problem with people wanting to stand, in grounds where it's possible and permissable, but think it's selfish and ignorant to do it when it isn't.