There's a difference between being a nice guy and a doormat. I"m a nice guy. I respect women. But if I'm going after someone I take command instead of waiting for something to happen. I don't shower them with fake niceness, I do just enough to make them appreciate it. And if they aren't interested I move on.
The thing is these so called "nice guys" are more obsessed than nice. They pick one girl and shower her with attention, thinking that will prove their feelings are real. But that attention should be reserved for a woman that's actually your girlfriend, not the one you're trying to get with. Too much attention from a guy they barely know is a turn off to women. You've got to first get in their head and build a close attachment BEFORE you start doing things for them.
The crux of this particular issue is that women do not know the the difference and it simply does not matter. A guy could NOT spend any money on a woman, NOT give excessive attention to her ,and NOT be a pushover BUT if he is mainly respectful towards her and people in general, he is STILL viewed as soft/weak and the said female will try to come at him sideways with bullshyt. And I guarantee that the same female would NOT try to play games with a guy with an overall DISRESPECTFUL disposition, which I have seen quite a bit. But women will still denies this.