Children love 🎈 probably due to the "colorful, floating, and bouncing" nature of balloons. I believe balloon translate to them as something fun. In addition, balloons are usually given to children as gifts which gives them a sort of satisfaction. This may also add to their joy in holding on to them and loving them so much.
Children are the most innocent souls on earth. For them, the world is a playground.
Kids get easily attracted to colours, soft notes of music etc. Balloons, being vibrantly coloured, catches their eye. Moreover, the balloon floats in air and this adds to their fascination. This makes balloons an ideal entertainer to kids.
Cartoons and real world experiences inspire a child to own a toy. Children assume the cartoons to be real and so would throw tantrums to get that favourite toy.
I do agree that while majority of children enjoy balloons, some may feel frightened from them, perhaps from a previous experience of the unpleasant popping sound if the balloon burst?
Kids and babies run towards the houses with balloons out front because they know that something good is going to be inside. Another reason older babies and children love balloons is that the time with a balloon is limited. It's a finite gift to have this thing in their lives, and they know that. It is also fun to play with!