A very negative review of Sony 16-50mm

Exactly.  Reviewers still haven't got their heads around the fact that MILCs have two distinct markets.  One is the mass market compact-is-king. The other is IQ-is-king. Rarely do the two meet (Sigma is the closest here in fact), and the reviewers only make themselves look dumb by assuming only the latter market exists.  In fact, the former is a much more profitable market through volume - you can look at many forums to see how many people are trying to buy after market PZs. Some people (like me) actually put different weights on IQ and portability depending on the context they're shooting in (gosh!).  Some days I just want a small versatile camera.  Some days I want a perfect crisp photo.  I have all those options in the NEX system.  Imagine that.

In terms of other examples, the Panasonic pancake zoom does pretty much the same things as Sony's 16-50 (severe distortions at the wide and long ends), and the distortions are even visible in the camera corrected JPEGs on several m4/3 cameras.  But as a result you can slap it on a GX1 and fit that in your pocket.  Well some people are happy with that compromise, indeed I would say they are a greater proportion of camera users than the purist IQ-is-the-only-thing-that-matters group.