I think it's down to development resources & specialists.
They've spent over a year getting the game into a playable state and reworking maps that launched with the game, with most of the resources now working on the next BF game. I think that's why we're seeing recycled assets throughout the live service, barring Exposure. The one map that actually looks different.
I also believe that sticking with the specialists means we can't have any CQC maps because the game will play like Quake champions instead of an arcade military shooter. I mean can you imagine playing Metro with grappling hooks, turrets, airbursts, scatter nades, wallhacks etc. It would just be an absolute disaster IMO.