There are 0 reasons to go 4x3 other than having a professional assignment in which a tv commercial or public display screen requires it due to formatting issues. From merely a visual standpoint it's like saying there is an advantage to shooting hd over sd. If you are presented with the choice, why choose the less visually appealing one when all the hollywood movies and tv commercials and the mass of the viewers are loving the upgrade of quality. Those eyes get trained to accept that as professional. To those eyes, 4x3 would look unprofessional. It's about staying ahead of the curve and giving yourself every advantage possible when you try to make this a career for yourself. If it's a recreational thing or a casual video then this doesn't apply to you but if the feature is there, use it to prolong the market value/appeal of your dvx and enhance the impact of your work.
now that every cheap camcorder has a 16/9 ratio, 4/3 is becoming unusual. I like 4/3 a lot. When color appeared on the screens hopefully it was not the end of black & white. it's just creative choices that an artist gets, to make his vision concrete. your argument is a technician argument, not an artist argument. What about "festen"? What about david lynch using a pd150? ..... It's like this shallow DOF race. In 2 years, even my iphone will have some shallow dof i'm sure. maybe i'll be happy to go back to a dvx without any adapter, it will have an unusual look, different from my uncle cheap 1.85 3K camcorder with super shallow DOF. hopefully, interesting artists don't follow this "let's give to the mass what they want" argument. cinema/documentary is about having a vision, a point of view, not having a bigger one ^^