Because of high customization.
Unlikely necessary, and still more complicated than is necessary. Reducing it to 8 still means manually doing that whenever you want to place a door, and it's still a lot.
Much better than that ew "click" sound from default doors or how legacy doors gives every door the same ew sound.
Personal preference
I agree. That's easily fixed though.
Being easily fixed doesn't mean that it has been or will be fixed, and doesn't excuse the current state.
I'm not sure whether this is about brick loading times (executing the add-ons) or brick loading times (in server) but it sounds fixable.
I believe it's in server, and "fixability" STILL doesn't excuse the current state.
Don't use it then, there is absolutely no reason to complain about it just because you don't see the use, many others find it VERY useful..
It does allow for very annoying stuff to happen, and is also, as he said, overly complicated.