The tents are great. It's the lack of consideration with location selection that is a problem. Don't set up on the front fence line when there are bleachers behind where others may have their vision blocked. And don't convince yourself that since you got there early, it is your right to block the bleachers, even though there is no one there yet. And don't give in to the mob mentality that, since there are three other idiots doing it, it must be OK for me to do it too. And don't occupy the entire main walkway, making people take a detour when passing through. If you are along a fence line with nothing behind you, absolutely knock yourselves out.
I went to a game at UCSD last Spring on a fairly hot day. Most fans were opting for seats several rows back from the front because there was some shade relief. I was sitting in the stadium seats overhearing conversation about an overly-entitled player and how his parents put up big $$ for him to be a late add to a college team and how they felt they could buy their way into anything and always acted above everyone. I usually ignore that type of dialog. Well, five minutes later, a large family contingency walked into the stadium, made their way to the front popped down two of those tents over some of the front row seats, completely blocking the view of about twenty people behind them. It was obvious and something they could not possibly be oblivious to. A few commented. They ignored. Several people had to get up and find other seats. Guess which family it was. I think that was the only time I really let fans get under my skin last year.