Yes, the absence of the mirror box gives more degrees of freedom. But most "normal" lenses re double gauss designs, even on SLRs.
My guess is that Zeiss choose the Distagon type design over double gauss to be able to reduce vignetting and keep beam angle down. Sony on the other hand choose f/1.8 much reducing the problem with beam angle and vignetting, they also have offset microlenses on the sensor which help with beam angle, so they could choose a less expensive design that is easier to make.
Best regards
Erik
Well AFAIK both lenses are Zeiss designs.
I expect the differences in design also owe something to the SLR mirror box clearance required for the Otus.