I feel the opposite. PLEASE DO continue the trend, Paizo.
As you noted, OP. If you don't like it, it's not a hard fix. And in those instances where Paizo is using boring old demons yet again, I, and those who agree with me can patch in cool space ships and pirate cyborg henchmen for our skeleton liches to boss around.
Also for a fantasy genre with "plenty of room" isn't there enough space for all the cool things?
They have also been apart of the setting since PF1 it isn't a new thing
This module appears to be at least a hat tip to a load of adventures gone by: You visit Magnimar from Rise of the Runelords, you'll get some Legacy of Fire call outs next chapter, I know for sure we're going to be visiting the giant demon rift with a bunch of crusaders there to fight it.
And yeah, the crashed Numerian spaceship. And Cthulhu stuff (including actual name dropped Nyarlathotep). Pathfinder is a unique blend. Expect a lot of stuff from a lot of properties to show up.
If the fact that a Barrier Peaks style spaceship has crashlanded in Conan-Land and made it all Thundarr the Barbarian freaks you out. Just you wait! There's some wacky stuff out there.