It would be really nice if we could use mounts in w1-4 the same as w5, so we can move around faster outside combat. Also, it would be nice to have the functionality of the portable magnetite vendor extended to work as a portable gaeting vendor, or at least unlock that functionality with voice in the void achievements.
I'd like to enable mounts in the old wings, actually. The reason we haven't is because we don't have the map art resources to dedicate to making the appropriate changes to the map, followed by the QA time to test it. It's on the "when we have resources" list.