Seriously? What a horrible way to tear apart someone else's hard work.
An actual case study of Stack Overflow would be that something designed by developers could be a huge objective success.
Also, his proposed improvement "hasn’t included all the functional elements yet" Anyone can make almost any interactive design appear to be superficially better as a static screenshot by taking things away. As far as making something that actually works and does the right thing, that takes more than Photoshop and arrogance.
It's sad to see this guy getting attention.