Visor is a bit different as it alters the appearance of the head piece. Toggle on the head piece completely removes it, while still keeping the stats equipped. I bring this up because in order to make this happen with capes, they would have to go through an rework all the chest pieces that they wish to apply this feature to (it likely wouldn't be all of them).

While this might seem easy, the issue is that those armor pieces have the cape as part of the design, so you can't just remove it without designing and implementing what the gear looks like underneath the cape. Because the physics of capes is very limited, I would imagine that the cape is not processed as its own object on the OS, but rather the cape and chest piece are all considered a single object (budget and time constraints factor in to this as well).

Toggle is much easier because it just removes the head gear, if it was applied to chest pieces, it would do the exact same. That being said, I think Toggle should be an available command for all slots that alter a character's appearance, and if they did decide to implement being able to toggle capes on and off, you won't hear any gripes from me. I think allocating resources and time to this addition would be just fine, as it would allow them more flexibility going forward with gear design.