Some comments by my female coworkers have inspired this post.
Paraphrased and mis-remembered:
Female coworker 1: Some complaint about her husband not being nice enough. (She didn't get a good enough Mother's Day present maybe.)
Female coworker 2: Similar complaint. Where are all the nice guys?
Female Coworker 1: They don't exist.
[End of conversation. Start of my unspoken thoughts.]
Me: There are lots of nice guys. They're the ones you ignore.
Me: Upon further reflection: find a guy significantly less attractive than you are and he'll be as nice as you want him to be.
Analogies to explain why nice guys finish last:
If you say, "I prefer girls with large busts," and a fat girl replies, "My breasts are huge!", then the correct response is, I meant, "I prefer attractive (thin) girls with big breasts."
Similarly, a girl who says, "I want a nice guy," means "I want an attractive guy who also happens to be nice."
A guy can be attractive without being nice. Niceness, or cup size, is secondary.
Let's say you're looking to buy a particular dress. (I know modern girls seem to be allergic to this idea of buying, or heaven forbid, wearing a dress, but let's assume for the sake of argument.)
You're likely to have a list of things that you want: in your size, your favorite color, your preferred sleeve type, your preferred length, etc.
It would be very difficult to find one that fits every preference. You're likely to need to sort through lots, and lots in order to find one that checks every box. And then when you do find one it will likely cost a whole lot more than you can afford.
Similarly there you'd need to sort through lots and lots of guys to find one that checks all of your preferences. And when you do find one, unless you meet all of his preferences, he won't be available.
In order to accomplish your goal, in either case, narrowing your list of preferences to "required" and "it'd be nice" means that more dresses, and more men, will fit the bill. The second category cannot be essential or you will not have widened the list of acceptable options.
Now let's say (for the sake of simplicity of argument) that your list of preferences in a man include the categories of: appearance, social skills, income, and niceness. Not a lot of men will meet all of your preferences in every category, but a lot more will meet your preferences in three of the categories, and a lot more will meet them in two of the four.
So, narrow your essential preferences to three of the four.
Which preference category was moved from "essential" to "it'd be nice"?
In my experience niceness is the lowest regarded.