This isn't a bug, but...
The versions of GTA 1 & 2 I ran last play-through (I didn't install 'em this time 'round) were in the EXE format. They can be converted to BAIN packages or OMODs easily enough I suppose (never tried it, being inexperienced at such things at the time), but it would be nice if they came in those formats from the get-go. (Maybe a BAIN 7z with OMOD conversion folder?) Other than being very particular about load order I recall nothing amiss with either GTA.
-Decrepit-
It's something that I've brought up with ThePriest909 previously, but he didn't want his models to be used as resources or something similar. Not that someone couldn't just copy them out once they'd installed the mod, so I can't say I understand the argument myself, but I respect his wishes as the author, so that's not going to change.
What I do is install it to a temp folder, then copy it elsewhere, make it BAIN-ready then compress it, before installing it with BAIN. I then can run the uninstaller in the temp directory to get rid of any registry changes (I hope!).