Why "HILO" instead of "JOYPAD" for `rIE`?

[Rangi42]

Pan Docs describes IE and IF as having bits for VBlank, LCD, Timer, Serial, and Joypad interrupts. hardware.inc defines constants for "STAT" instead of "LCD" (an understandable alias, one that Pan Docs uses elsewhere, though having alias constants for both would be nice), but also for "HILO" instead of "JOYPAD" (describing it as "Transition from High to Low of Pin number P10-P13"). Is there some reason why this isn't more clearly named and described as joypad-related?

[ISSOtm]

I think calling the former “LCD STAT”, “LCD status”, or “LCD / STAT” in Pan Docs would be a good idea. hardware.inc used to call it IEF_LCDC, which is plain wrong.

Likewise, I believe that HILO is purely a historical artifact from the time where there was more than one authoritative source, and one which hasn't been fixed since because that interrupt sees near-zero use anyway. I'd like IEF_JOYP or IEF_P1 to be provided instead. (Though I don't like rP1, see #47.)