If it's my first time somewhere, I politely tell the group I'd like to watch the cutscenes. I'm not really giving them an option about it, but manners don't cost anything.
If it's a repeat run and the rest of the group is keen to skip, then I skip too.
If it's a repeat run and someone else says they want to watch, then I will watch too.
I have encountered flashpoints where some players get absolutely FURIOUS about people not skipping, and honestly I find it hilarious
In some cases they even leave the group, which makes no sense at all, because now they have to queue again and restart from the beginning. Baffling.