Could just add custom msg code in terminal. But holotapes work. Using this feature we would lose value in holotapes.
I will be bold here and say i lead this community in my love of holotapes. Who else has a scribe character? It's ridiculous. However, holotape functionality is not too good. It's too limited to write a tape, leave it on the ground, hope the right buddy finds it, hope other guys leave it alone, hope the right buddy replaces it with a reply tape, hope nobody messes with that one. Etc etc. It's far too fragile to try to use holotapes for in-game message handling. (Remember that is said by the #1 fan of holotapes.)
Try to edit a holotape. No mouse-cursor control, so if you find a typo, you have to right-arrow all the way to it. How to delete stuff in a tape? Yeah, hold Delete key down until each character is removed one by one. (No way to highlight blocks of text.) No way to adjust the order of uploaded tape records in your Archives. No way to delete them, or overwrite them. So yeah i love these tapes, but no they are not going to be handy at all for message handling without a re-work.
Fixing all that: I was told by a dev once back in 2238 it cannot be fixed without re-writing the engine itself. "It's hard-coded in the engine."
One idea i suggested a long time ago about this was to fix a few public (or faction) terminals so that we could upload holotape data to them, for other players to download. By default, anyone could
get info from such terminals, and only approved people could
add info to them. Brother Martin, the monk-scribe in Hub, would no longer have to be present to share his library of wiki-on-tape holotapes. He could load them on a public terminal in Hub, and anyone interested could get that info any time.