Too many 'nice guys' are socially awkward narcissists that believe others exist to serve them and choose this way of acting because in their social awkwardness and lack of understanding how people work, they thought they found a method that works.
In a sense, it is exactly the same reason douchebags do the who negging thing...they get this in their mind that lowering someone's esteem will allow them to sneak in while the defenses are lowered. However, this actually works Being a 'nice guy' doesn't.
I'm a 'nice guy' that does nice things, but I'm also a complex guy that can be an asshole at times and someone that is upfront about my desires -- I've been told I have no social filters more than once. You know what? Learning to be upfront works...it allows you to sort things out, even if the other side doesn't want what you want, you can work through it. And this works. On the 'nice guy socially awkward' side, it is fucking annoying for everyone.
An example of this is that a good friend of mine after 47 years on this planet decided that he might not be straight any more. He has had several encounters with other dudes and you know what? Yay for him, however I don't give a damn except in the fact that I'll support my friend. He has now been making hints over and over towards me that maybe the reason I've never found a woman was the same reason he hadn't (plenty of long term relationships for me...I just don't believe in marriage). Or out of no where, he will make comments about how you never know if you like something or not until you try it. And a shit load of other very pointed comments.
Worse yet is he will make passive aggressive posts on facebook OBVIOUSLY meaning me because he tags people in all his posts, and I'm always one of the ones that is tagged in it. The dude is a 'nice guy' or at least he is until a woman spurns him, and his now change of sexual desire means he is doing the same thing with guys now.
And you know what? This is the same level of bullshit that women put up with. Even if I felt like switching teams, I would NEVER consider going for something that fucking pathetic. Even if everything else was perfect, this is a level of socially awkward that I couldn't imagine having to deal with it in any regularity. The 'nice guy passive aggressive narcissist' is the worst personae ever. I'd rather deal with an asshole any day of the week. My last girlfriend of several years was a complete asshole. She embodied the term bitch. And I loved dealing with her. I knew what she wanted and where she stood on things. And I didn't have to BEG her to get information out of her. If I were a woman, I'd fucking tell every douchebag nice guy to grow a pair of balls.
So stop being a nice guy and using it as your defining quality and start being a complex person that can be nice.