No you are not getting miserable with old age mate. I wouldn't done this sort of thing when i was 15. As someone above says, it's not a kids party.
I would have hated this idea at 15 too. At that age, I would have thought it was REALLY important to look tough at the match, and fit in with the other 'tough' lads. And I would have really worried that the opposition fans might have seen our smiley fans with their glowsticks, and laughed at us, and thought we were all a bit GAY.
I'm 41 now though, and a bit more relaxed, and grown up enough not to get uptight about a few people having a laugh with a stupid idea, that really doesn't affect me whatsoever.