Socially Acceptable? Seems most cosmetic choices are now-uh-days or are being argued that they should be so I won't say it isn't haha.
As far as what I think of men with long nails, it's probably safe to say they are not individuals doing manual labor regularly with their hands, or as their job because of how often they'd be breaking them and realizing it's more of a potential pain-causing liability for their hands rather than a good cosmetic choice.
For me that's a hard no on growing my nails. I might let a small bit of white be on the ends, but NEVER any longer. Do a lot of work with my hands and I don't need one of those little bastards breaking half way down the nail and causing me pain anytime I use it for weeks on end. I don't, never have, and never will go the long fingernail route. Those suckers get cut down as often as a small bit of white shows up so that my hands are battle ready haha.