It really isn't. I think it's ones of the series strengths. I just wish they'd play with it and give my movie set in the past!
Or the future! Imagine a movie set during the Rage Wars. Seeing all that tech. I think that could be done as a sort of spin off to show us what the far future looks like.
I really love the 22nd and 23rd centuries, as well as Resurrection's 24th century. But I'm curious to see what the late 27th century will look like in film or even animated.
That's another aspect I love about Alien and Predator. Not only the groundedness in science, but also the constant evolution throughout the eras. It's literally like a history of the series.
Alien and Aliens era is like a favourite period of time in-universe for many of the fans. It's literally like Assassin's Creed, it's got limitless possibilities because it's a big history lesson essentially. You can literally go to any point of time and at any place and do a story.
Wanna see a Predator hunt the Mayans? Sure, no problem!
Wanna see a Predator hunt during the Crusades? Sure, no problem!
Wanna see a Predator during WW1 and WW2? Sure, no problem!
Wanna see Aliens and Predators terrorize the modern day? Sure!
Wanna see how humans adapt in the near future? Got ya covered!
Wanna go to the far future? No problem!
Wanna see the end of the freakin' universe? Sure