The point is (to me, at least) that if you like/are comfortable with your non-digital srl and its lenses, you could use that thing when you feel like doing it instead of shooting film
.
It's just another "option" in the W I D E world of cameras.
I'd like to use my nikon in "digital mode" from time to time.
I guess the thing never got properly engineered, though, I can't find much infos online.
Full frame dslr are not that cheap hehe.