Sure, my nipples can get hard and sensitive. I don't get turned on by nipple-play alone, and too much attention can be more of a turn off, but if I'm already aroused, a little light nipple-play can positively add to the other sensations I'm feeling during sex.
Don't believe everything that you read.
Absolutely. Sex without foreplay is fun, but I much prefer a good foreplay session, and having my nipples tongued is something I greatly enjoy.
My wife and I loved it when she would bite them. It would give me an instant hard-on. She used nipple clip on them and then would knock them off with a riding crop. I do love pain.
One time I was at a camp out when 2 female friends were challenged to hold my arms down and sucked both of my nipples at the same time. Then they bit down on them. I moaned. One of the girls laughed and sat on my lap. She instantly felt my erection! She hugged me a said "You loved that didn't you!" She told the other girl who came over and grabbed ahold of me and announced to about 20 people that I got a hard-on.
Talk about embarrassed. I loved it!