What is the fascination with Black? Her parents spent roughly $2,000 to pay a music studio for a song and a music video. The song has very simple lyrics, and many of the people featured in the video are her actual friends and family. Maybe it's a mix of how bad pop music has gotten, or people love watching a train wreck.
For those not too familiar with the music world, there are now tools that can make just about anyone sound like an amazing vocalist. I know, back in the day, Milli Vanilli just hired other people to do the singing, but now you don't even have to do that. But Rebecca really isn't that bad of a singer, as seen in this acoustic version of "Friday" from ABCNews. She's by no means an amazing vocalist, but she's decent, and has some potential.
And hey, isn't this the American dream, or at least a small sample of it? That you have a passion, you put effort into it, and maybe you can "make it".
Finally, Rebecca seems to be a good kid. I'll close with this excerpt from a Rolling Stone article:
She is a total sweetheart. While it would be perfectly reasonable for any 13-year-old to emerge from a week of sudden fame and intense, often cruel scrutiny with a total nervous breakdown, Black comes off as a well-adjusted, happy and grateful kid. According to the Daily Beast, Black intends to donate a large chunk of her profits from the sales of "Friday" on iTunes – where it is currently at Number 31 and is said to have sold over two million copies since Tuesday – to school arts programs and relief efforts in Japan.