Actually, I expect more control on my text ads. AdSense style is boring, and why not Adsense provide more feature that make its ad more matching in to design. For example, underlined link is 90's old skool style, and most of web design today clean up those underline for their links. And why AdSense provide only Arial, Verdana and Time font style? Why not, for example, AdSense provides 'inherit font style', so ads will appear exactly like my design.
Bidvertiser provides better ad style control, publisher may stylize their ad or even ad dimension (width and height). Its cyber-democracy beibeh :).