Shifting fashion certainly has its influence, but I think it's mostly that with digital having taken over so much of the work-for-hire market, Photoshop and its brethren have for better or worse absorbed the duty of softening up people's facial flaws. This is just my opinion, but I think a side effect has been that much of the analog segment has responded to this by becoming even more obsessed with sharpness than before.
Hoffy, if you're interested in soft focus portraits you should by all means try them. An age without romantics willing to try things is a much poorer time to live in. We're awash in images that have been poured over for sharpness. Different is good. Who cares if somebody says it's cheese? It's no fun living on nothing but hardtack and water.
I've got a nice Mamiya 145mm f4 Soft Focus I really need to bust out more myself.