MMA fighters don't choose boxing for plenty of reasons, its just like why they didn't choose any other single martial art. As talented as guys like Anderson Silva et al are they don't throw punches like boxers or have defense like boxers. Plus going from 4 oz gloves up to boxing gloves you've got to feel that extra weight.

MMA is what it is...I don't like it for many of the reasons miles stated AND that the boxing knowledge is so poor from the fighters.