I don't really care. Is that bad of me? If its a HUGE party I tend to have a present opening session, this way thanks can be given. With the kids we generally open after, mainly because it's harder to keep track of who gave what when everyone is excited.

I wouldn't say one is ruder than the other. And I wouldn't be offended either way.

I don't understand why it causes issues with kids. I'd be pretty disappointed in my kids if they behaved badly over another child's presents. Maybe that makes me a bad mum