Those black things on his shoulders aren't actually part of him. ;)
Why blame it on poor J.J.? He didn't make R2, and why should he be expected to know exactly how R2 should look? I can't figure out what's wrong with him without a comparison picture, and I think it's perfectly reasonable that R2's been modified some time in the past 30 years. At least he looks used and not clean and shiny.