And players are also 100% entitled to use the spacebar key - using your logic, it's been put there to be used, so I suggest people USE it. I also suggest you take your own advice and ask if people mind watching, if not, deal with it. Neither of you is 'right', it's a group preference. If you can't play well with others, you're free to find another group.
Generally, I'll accept either choice.
For reference, I do spacebar usually. But I won't stand for people trying to force it on others. Regardless, if I don't want to spacebar, I don't need the group's permission. Not asking "can I please watch these" is not rude or "wasting everyone's time". Watching the cutscenes is the default action. Spacebar is the exception.