Walking through the enginerooms would be indeed nice. There are some points in favor of such a walkmode though.
In an engineroom, you dont see anything outside, the graphic burden can be reduced accordingly.
Moreover, mechanical parts have simple forms and need relatively less textures, that is why it could be envisaged. Indeed, nowadays, you see less -if any at all- moving parts in enginerooms.
Would the biggest problem not be then new requirements regarding many engineer's tasks?
It would be perhaps possible for modelers to develop sets of standard engines, pumps, tanks, tubes, valves to equip enginerooms, staircases, ..?
Regards
Luc