[Teddy was very very young and impressionable okok even though Gohan beat out Vegeta by a mile and hey what kind of name is Trunks come on man]

I guess it's just a thrill to celebrate it when you're young. You're not taken as seriously when you're just a kid and all, so you want to get older. Be more independent, get treated the way you want to be treated. Kind of goes against you when you do get older, though. That's when people just want time to stop for them.

[... Maybe that's why Vegeta doesn't see it as "important", though it could also be because of the Saiyan thing.]