Re: How about

Yeah, coz typical end-users are really going to spend time and energy discriminating between a root certificate from a reputable authority and one from (say) DigiNotar.

The current practice of bundling is probably the only thing that stops Verisign having a total monopoly. (Since most of your customers will have heard of Verisign and won't have heard of anyone else, and those customers are the ones deciding whether your certificate is trustworthy, who are you going to get to issue your certificate?)