Well, its an argument quite a few people have. DBZ has a lot of fantasy elements that some beleive can't translate well to live action. Heck, that's probably the reason writers and directors feel the need to make changes to it. Where as CB is pretty much an live action Western movie animated, which is one of its many appeals. People who don't normally like anime like Bebop because of that, imho. Therefore, it should be easy to adapt it with everything intact.
PHW is also touching on the fact that there is somewhat of a negative stigma of sci-fi in our culture, mostly because of what I like to call "technobable syndrome". People shy away from sci-fi elements, so it might be a fear to some fans that they may change a few things to lessen the sci-fi elements of CB to suit audiences. SHE was trying to say that with successful movies like the new Star Trek and Firefly/serenity, Sci-Fi can be done right if written correctly.