Another important point that I would have thought the Psychology today article would have picked up on, is the fact that the women who regarded themselves as attractive, from a psychological standpoint, are narcissists - they, to at least a small degree, love themselves.
I don't mean this in the sense that they're "stuck up bitches" or whatever others have said, but to admit to another person that you think you are very attractive, indicates personality traits hinting at narcissism.
Therefore, the thing to take from that study shouldn't be "attractive women prefer bigger penises", but more "women who think of themselves as attractive put more importance on penis size". So I wouldn't personally presume that all women who are attractive are 100% focused on penis size, but those who clearly think they are attractive (regardless of whether they truly are) are more likely to have penis size requirements.
In saying that, im not saying that "if you put penis size high on the list, then you surely think highly of yourself", but the opposite, "if you think highly of yourself, you're likely to put penis size high on the list". This being, as some have mentioned, due to the fact that if you are (in your head, or in reality) extremely attractive and have the pick of the world's men, then you can go down your list of criteria until you find the right guy. Whereas those less attractive, or less confident in their attractiveness, will find a guy that meets the first few criteria (not getting as far down the list as penis size), and settle for him, due to percieved lack of options.
In much the same way (to use a cliched example), i'm sure brad pitt can be choosy when finding a partner, whereas someone like Howard Stern (ignoring the micropenis issue he has) will probably settle for a decent personality and a nice smile, anything else being a bonus.
I guess the male equivalent being the woman having a nice ass or breasts, good looking guys can be choosy about those things.