I've been working on some no-digital (but heavily retouched, using masks, matting, sandwiched negs, etc.) ideas, and I want a somewhat vintage, ancient, "very early photography" look. I could do the work with Nikon AF (N90s, 8008s, etc) or an RZ... but it feels way better using old metal. Canon FT, Nikon FG, my RB gear. Just "feels" right to have those funky bodies in hand.
I've been a musician all my life, and it's the same way with that gear... "this guitar" is what I want for this feel, that sort of thing. It's more than just the specific tonality, it's how I feel playing the things. Ghosts in the machines, if you will. The old gear has a mojo the new stuff can't touch.