It is an admirable lens in terms of sharpness, but it seems quite expensive to me for an f/1.8 50mm. For other major brands you can get f/1.4 for a lot cheaper than this lens, and f/1.2 for not too much more.
But, if sharpness is your only concern, this is a good lens.
That's like saying "The lunar rover seems quite expensive, for a vehicle without leather, you can get cars that are much better equipped for a lot cheaper, and cars that are gold plated for not much more, but if driving on the moon is your only concern the lunar rover is a good vehicle".
Anyways I wouldn't read into DXO's sharpness figures too much, they are meaningless junk that take the sharpest possible point on the lens and use that as the benchmark. Their rankings would be wildly different if they measured sharpness as an average.
This lens is a marketing gimmick though. It has nothing to do with the Zeiss Otus and the technology it uses. The standard focal length prime (i.e. 50mm prime) has been an extremely difficult problem to crack for single reflex mirror cameras, at this range with the standard back focus distance you experience extreme optical aberrations that reduce resolution by 2-4 fold and add tons of hazing chromatic aberration and purple fringing to images with standard optical designs. In fact if you compare the 30 most popular 50mm lenses, the Zeiss Otus achieved performance that was at a minimum 2 times better in every meaningful dimension, in many cases it was 5 times better. It used a revolutionary new incredibly complex optical design. That's why the Otus is special, it's like sending someone to walk the moon. It's special because it's a 50mm lens that's sharp with a normal back focus distance. A lens like that doesn't exist outside the Otus (although Sigma is releasing a lens with a similar optical design, the 50mm f/1.4 ART, which is also revolutionary).
The 55mm f/1.8 ZA is not revolutionary. It's about as impressive as sending someone to walk on the sidewalk. There is no complex technical problem with making a sharp 55mm lens with a short back focus distance. The lens has only 7 simple elements. It's child's play. Optical design becomes equally simple at 85mm for a long back focus distance, so basically 55mm on mirrorless has the same challenges as 85mm for mirrored, which is to say there are none, it's a given. The 55mm f/1.8 ZA is boring design that shows no skill or technical mastery.
As far as being the second sharpest lens DXO has ever tested, that's nonsense. If you look at DXO's sharpness figures and drill down to the raw data the Nikon 85mm f/1.8G obliterates the 55mm f/1.8 ZA over 98% of the frame at all apertures, yet the 55mm f/1.8G ZA has a much higher DXO score just because it posts a higher figure at a single data point. That's not to say that it's not a sharp lens, but it's not special in any dimension.