I'm not sure why this photo didn't score better. Your subject choice is definitely mundane. I think you did a decent job of photogrpahing it as well. The only thing that could possibly be improved is the overall sharpness. F/8 is a relatively large aperture. I can't see any particular benefit in not having this entire subject in sharp focus. F/11 or f/16 would probably bring this one up to speed.
Ain't that the truth, especially with kids and cats in the house, the perfect toilet paper roll is just an elusive dream.... I really like your idea and the composition is quite nice. Kind of loses detail on the left side of the roll, but overall, very cool picture!