I don’t blame the engine. There are other studios out there with custom engines that evolved over time. Also Creation Engine evolved a lot.
That they work with many connected scenes instead of a continuous world also has advantages … it allows them to easily change the “world” between scenes by simply linking you “back” to a different scene (for example city under siege which before the dialog was not under siege). It’s how they work. They could do the same shit with Unreal if they wanted to and if they believe this kind of game design is the only feasible for their story telling, they would shove it into another engine as well.
I also don’t think the game feels “old”. I do think it feels like it is conceptionally unfinished. They had many ideas and you can see a lot of different systems in the game (space fights, planets with different biomes, ship building, base building, and so on and so forth). Each of these systems in itself has some kind of concept, but all these systems together are missing a clear concept, IMO.
From what I know, game dev typically works in modules that get thrown together. And this also seems to be the case here. However the “big picture” wasn’t refined or they realized that it needs a ton of small adjustments all over the place (conceptionally AND technically) to make sense of it and it looks like they were not able to deal with the complexity of that.
As a result we have a game that is okayish. It tells some stories, and offers a lot of content, but it feels not nearly as stunning as it should have and it’s not on a single front ground breaking.