My own are hard wired, too. For me, it's almost as intensely pleasurable as being blown by a really expert cocksucker (and there are far too few of those in this world, IMHO!)
And oddly enough I discovered it in nearly the same way at the old Mindshaft in NYC the way someone else here did! (Maybe it was the same guys on another night! Or later the same night! Small world isn't it?)
When I'm with guy for the first time, I can quickly gauge the quality of the sex by how responsive his nipples are. If I brush or touch them and they become hard - I'm in for one wild ride! <grin> If I suck them and he moans, he's gonna be moaning with pleasure and grabbing my cock with his butt muscles in a few short minutes (and doing a real good job of it, too!) If he grabs my arms, pinning them at my sides and starts sucking/chewing on my nipples at the first touch to his own - pass the lube and take the phones off the hook - we're gonna be screwing each other's brains out for the next twenty-four hours or so. And after a few minutes of enjoying the service, I'll reverse the position and work his properly until he's ready to beg for mercy...etc.
Yeah, man nipples are a great gauge of how the guy is going to be in the sack, in my rather vast and extensive experience. I'm told by several women friends I know well that the same thing pretty well holds true for straight guys, too.