Optimistic perhaps, naïve definitely not. As yourself, I am certainly not a novice on relationships, I've had my share of heartbreak and have been burned a few times too. I have extensive dating experience, and have made my share of mistakes. I have been married 3 times, divorced once, lost another spouse to premature death and currently happily married to my current and last wife.
I did say that I would not give out personal info to a complete stranger but it would depend on how well I knew this person. A person that desires a relationship but is afraid to act will remain lonely and alone for their entire life. There are risks in pursuing a relationship, calculated risks that I was willing to take.
Let's say that a guy is lonely. One day this guy sees a pretty girl close to his age at the 7/Eleven that has his interest. As he was paying for his Slurpee this girl smiles sweetly at him, comments him on the T shirt he is wearing and slips him a piece of paper with her phone number on it. This guy now has a choice, should he call a this girl that he hardly knows or be afraid to take a chance, crumbling the paper as he walks out the door and puts it in the trash can next to the Pepsi machine.
I would not say that I'm entirely optimistic either but do know from experience that a man with a feint heart will not win the hand of a fair woman. No, I'm not naïve but realistic. I have been around the block once or twice. I've been there, done that, and bought the T shirt.