So many hypocrites on this thread.
Look at yourself first. I can guarantee you do something that is not really needed on a daily basis that fucks up the environment and wildlife. But you all carry on while judging others, while you fuck up wildlife and the environment yourself 
Yes, loads of people litter and the earth is fucked but why add to that. It's so weird.
Because you don't add to it, no? Ahh I see, it's ok for you to do the daily stuff you do which adds to it, but not for people who release the odd balloons?
As for it being weird. Well, imagine this.
Your children lose their dad after watching him suffer with cancer for four years. They have two weeks to get their head around the fact that he is dying. Their last wish is to have one last Xmas with him. They don't get that wish, the last time they see their dad he can barely walk and the last time they hear from him was when they called and we didn't realise he would be howling in agony and not even know who they are anymore. Then to top it off? Two grandparents die of cancer just after. The one thing they ask for is to release a balloon so their dad can read a message from them. They want to say goodbye and tell them they love him and they can't think of another way of doing it because they are young and they think he might just be able to read a message on a balloon- they have to believe that to get through.
You do it, to give them comfort because their world is shattered and you would do pretty much anything to give them that moment of comfort which means so much to them. They don't want a tree, they don't want to light a candle and yes, they were young enough and desperate enough to believe the balloon would go to heaven.
Now tell me it is fucking weird of me to let them do that?