Because it will look like the WWI arena that every one though would be good to have.
Yes.
That's how it was in Air Warrior, which had a WWI arena and a Korean War arena. No one used them.
Korean War jet fights were glacial compared to WWII because it took so long for a jet to do a 360 compared to a WWII fighter and because most of the dogfight had the two planes 1000 yards or more apart. People did not fly prop planes in an arena with Mig 15's and F-86's -- they go in the other arena for that. So, it was an arena with, at best, a few people in it engaging in glacial jet fights.
WWI has the problem that the upper wing gets in the way of your forward-up view, which is hugely annoying in dogfight pursuit. WWII planes are just more fun to fight in. So again, that arena had no or only a few people in it.
WWI and Korean War sounds appealing to folks who didn't experience them in Air Warrior, but they aren't much fun compared to WWII.
WWII is the golden age of air combat, where the planes were slow enough to make close-in fights possible and 360's possible in short times, but were advanced enough to have good visibility and performance good enough for vertical maneuvering.