Access to different areas of the stage, not just when fighting but like MKA (arcade mode) much more fleshed out and take into account the objects, NPC's and that around too. Or able to simply select other areas of the stages/arenas, as unlockables.

Shang Tsung's lab gives Frankenstein Horror Vault and Independence Day vibes (the Harvesters in the big tubes). Don't know if this still occupies in Flesh Pits though.

Anything would be better than the Tea House ! That belongs in a Street Fighter game not MK