Are you seriously equating optical quality of the product based on the mass/size!?! Regarding the Otus - whether you feel the size is agreeable or not the product is outstanding and it was the lens that probably started the whole push towards higher resolving lenses for DSLR's. The Sigma Arts offer 95% of the optical performance with the added benefit of AF at 1/5 the price but again they are large.
This might be the weakest anti-Sony argument you've contrived... this month... I won't make the blanket statement though because the month is still early.
No, I'm not equating optical quality of the product based on the mass/size, but it's apparently the way things are heading. If I should guess, it's done because it's the easiest way to achieve ultimate quality, and everybody except Leica seem to be going in that direction, in spite of camera bodies getting smaller, at least compared to what they were 5-10 years ago. Leica is the living proof that high quality lenses don't need to be large.
This is not an anti-Sony argument. All high quality, large aperture lenses for the 35mm format (again, except Leica) seem to grow larger, regardless of brand, even those that are only f/1.8, like the new Nikkor primes, 20/28/35/50/85. It's a paradox, since cameras are usable at much higher ISO than before, which means that the market for f/1.4 lenses should be diminishing. Apparently, it's not.
For me, a complete setup of moderately sized f/2.0 lenses that are sharp across the frame from f/2 to f/11 is much more interesting. The Zeiss ZF/ZE range offers that, as do Leica with the Summicrons. Nikon isn't too far off with the above mentioned primes, although they are a bit larger and with a distinct feel of plastic. They are quite lightweight though.
Sony could have done something like this too. As soon as they knew that the A7 would become reality, they could have made a phone call to Zeiss, asking them to design FE mount versions with AF of an assortment of ZM lenses, modified to suit the sensor, the mount etc. They could have had something like 15/2.8, 21/2.8, 28/2.8, 35/2.0, 50/2.0 and 85/4.0 within months, or at least a year. I can assure you they would have grabbed my attention. But they didn't.