I don't know how much I would rely on the rabbinic literature (referred to in the Wikipedia article). It at least seems unlikely that Orpah would move from Moab to Phillistia. If she turned back from following Naomi, it was probable that she did so to return to her family in Moab.
It is at least not generally accepted in Christendom that Orpah is Goliath's mother.
Otherwise, I don't know that Orpah should be vilified for her decision. It seems somewhat selfish compared to Ruth's, but it need not be thought of as abandonment. Having a family was a big deal to a woman, and going with Naomi to her foreign home was not necessarily the most practical choice. Being a widow was synonymous with poverty. Naomi herself told her daughters-in-law to return to their homes. Orpah at least exercised some amount of pragmatic reasoning instead of living out an obligation to her mother-in-law.
I am not a part of or close to African American culture, so I cannot speak for them from close ties. It seems that, as a group, they have a tendency to identify with the oppressed, so perhaps it was a decision by Oprah Winfrey's parents to remember this other daughter-in-law who gets almost no attention because of Ruth's choice.
Another possible reason could be that (almost) any Bible name is better than all non-Bible names. I don't necessarily subscribe to this philosophy, but there are Christians with such practices. It's not always done with a thorough understanding, but it is, at least, a sincere act, and we all trust God to listen to our hearts.
Here is a quote from Oprah Winfrey concerning her name.
Oprah Winfrey: I was born, as I said, in rural Mississippi in 1954. I was born at home. There were not a lot of educated people around and my name had been chosen from the Bible. My Aunt Ida had chosen the name, but nobody really knew how to spell it, so it went down as "Orpah" on my birth certificate, but people didn't know how to pronounce it, so they put the "P" before the "R" in every place else other than the birth certificate. On the birth certificate it is Orpah, but then it got translated to Oprah, so here we are. But that's great because Oprah spells Harpo backwards. I don't know what Orpah spells.