After spending on a FF Dslr? I think a 50 F1.4 will be affordable? And most film shooters know how useful a 50 F1.4 is. Just try it on film once and you will understand how FF users will use it more.
I agree how useful it is coz it is one of my often used lens, having used both the Minolta 50mm F1.4 on film and digital crop factor dslr and the Nikon 50mm F1.4 on full frame DSLR... as can be seen in my blog, hehe... but I still do not discount the fact that a full frame user who does not use 50mm much may opt for the cheaper 50mm f1.7 version for his/her occasional use. Its one less choice to have. But anyway its out of topic to the original threadstarter and I apologise.