It takes more than being nice to make people want to date you. Knowing a nice guy is, yes, nice, but it's not really a hook. There has to be something interesting about you. A shared interest, a talent, a good sense of humor, an appealing outlook on life. All of this is relative to your partner's tastes, but personally I have never been interested in someone just because they were kindhearted.

It's definitely a plus for some people, though.