why is castrum and praetorium not an instance

[Niwashi]

it def needs a fix a new player has like a 20 percent chance of being able to watch the cut scenes so what was the point in the 130 quest to not even see the ending

I think a 20% chance is overly optimistic. Maybe there's a 1% chance, but I think it's probably lower than even that. I even went with a Party Finder group so I could specify that we'd not skip any cutscenes (in the PF checkboxes, in the PF description, and in discussions before starting), yet there wasn't a single other player besides myself who followed that rule. They all ran on ahead, (and did so while leaving the mobs behind, so that I couldn't even explore the opening room to find where the exit was to follow them).

I would rather have them work on new content than that.

That might be valid if these were just ordinary dungeons, where it didn't matter. But this is the climax of the entire game we're talking about, and it's completely destroyed by the way it's always run. SE really should have fixed this before they ever added an expansion to the game. As it stands now, everything after it is broken by the fact that the story that's supposed to lead up to it is broken. Adding more and more broken stuff rather than fixing the problem doesn't improve the game.

Technically SE did learn as there are no dungeons like this in Heavensward.

And once they learned that, they should have fixed it. They still haven't. (I'm currently hoping the GC squads will be set up for these two, so we can solo it along with them, but there are plenty of ways it could have been fixed. Changing most of it into a solo instance, perhaps meeting up with a group part way through so that what's now the final boss fight becomes a single-fight instance like a trial would work, too.)

Actually, you're beating the dead horse's ashes, that's how often this complaint has come up in the past years.

It's come up that often because it really is an important problem. The fact that it's been a major problem for a lot of people doesn't make it less important, it makes it more important.