Yes we could add those features but it would be a redesign - for example the BP26 would also need a remote receiver design as well as a different volume control with some kind of lighting etc. The BP26 was designed many years ago and remote control was not all that common back then. The BP-17 preamp which is a newer design does have remote volume and full remote source control as well. A lot of it is a timing issue.
The BHA being a headphone amp was design with the assumption that the headphone listener would be in close proximity to the unit (due to headphone cable) but in hindsight when we added the preamp out feature it would have helped to offer a remote volume but that again would involve a redesign as well.
AFAIK, the BP26 does have a remote receiver, and so does the BP25.
Neither of these, nor the BP17, offer a LED on the volume knob.
Personally, I don't care about other remote controllable features other than volume pot. - with a LED on it. The BP-17 doesn't seem to have a LED there.
And I much prefer the BP26/25 design.
The BHA1 would benefit of a remote receiver and a LED on its volume pot. - because a 3 meter headphone cable _is_ far away, when I'm lying in the dimly lit whereabouts, very properly immersed in music and only my right thumb may push something.
Let alone when the preamp out was implemented.
I hope I can wait for the redesigns ...