OP, you can do whatever the hell you want. If I ever find myself in Praetorium or Castrum, and I see some new players who are there for the first time, I let them watch those cutscenes. It doesn't bother me. Enjoy the game. It really isn't that big of a deal.
You're playing at a time now where once you're done with Prae and Castrum, you won't really need to go back since there's plenty of other dungeons that provide myth and soldiery at a faster rate. Back then, when we had to collect Philosophy Tomes, Castrum and Praetorium were the dungeons of choice because there were no hard mode dungeons and you had to gather that Philo to find gear that would get you through Amdapor Keep and Wanderer's Palace. Otherwise, you had people yelling at you for not having Darklight (lol)
Anyway, my point is, since that's not the case anymore, you shouldn't have to go through Praetorium or Castrum at all really after the first time unless you're helping someone or you get lucky in your Duty Roulette. If you go back in there you'll find out that skipping the cutscenes makes it go much faster. But still, nobody should push new players to skip. A story dungeon is a story dungeon after all. Especially with something so vital to the very end of the base storyline. Those of us that had to deal with the cutscenes back then while farming that place just got annoyed, especially because we didn't have that "skip already viewed cutscenes" toggle in the config yet...so you can imagine how annoying that got. If only we had it back then. Lol. BUT, because of all the complaining then, we have it today. So yay~
All that being said, the one time that I actually was guilty of forcing people to skip cutscenes was when I got trapped in a Praetorium about 15-20 minutes before a server maintenance. That was fun. Everyone understood and it made it a whole different experience trying to race to the end before the servers went down. It was a lot of fun.
TL;DR, don't force new players to skip cutscenes. It's really not a big deal.