First, the article is out of date. Entries were for 2011 and 2012. A lot has changed since then.
Also, it's opinion. There are a lot of 'studies' out there regarding preferences, most are simply opinion.
I'd break it down into four reasons why, and these four reasons seem to be pretty universal throughout this site and elsewhere. They are:
1. Contrast
2. Taboo
3. Perceived Size
4. Perceived larger Sperm Production.
I use 'Perceived' on items three and four for two reasons.
1. They are perceptions, not based on reality. Every study I've read (hobby of mine) suggest that on the AVERAGE Black penis is 1/4 of an inch longer than the AVERAGE white penis. I doubt if anyone can feel the difference.
2. I have never seen a quantitative study of ejaculate amount, although I've looked. If someone has a link to a valid study, please share it!
What a lot of folks don't understand are two basic truths. First, the porn industry selects men that feed the fantasy. No one wants to see a 4" Black cock! But they are out there! Second, women 'select' for that in their relationships. Sooner or later size will come up. If he doesn't measure up, she'll go elsewhere. After all, that's what she's looking for. I know I'm guilty of that and I'm sure a lot of other women are too.
I'll just finish by saying that the four 'interests' are what I've encountered in discussions with other women and what they've posted. Is it the result of scientific study? Of course not. In fact, all the above can be considered my opinion as I have no definitive way to prove my theories except for penis size ratio. That's pretty common information.
(No, Cosmopolitan isn't an authoritative source!)