SE will be doing this on the smaller sites eventually. And well, some of the issues people have with it feel feels a bit like 

[![enter image description here][1]][1]  
[source:xkcd][2]


It also actually takes up *less* vertical space and uses horizontal space better (It dosen't use *more*, but moves things around a bit. Feels bigger to me) 

[![enter image description here][3]][3]

And probably brings with it customisable tabs (and I will certainly be complaining loudly if we don't).

There's a bit of a learning curve (and when this hits SU, If the TPTB don't, I'll probably dig through and do a quick meta post on this - and if it hits here first, I might try it here first) but "disgusting, unergonomic, suboptimal. And it is fixed to the top" is 3/4 unclear and 1/4 wrong. If there's specifics you are unhappy with, go tell SE on MSO. We're pushing for a few things we need like [help links on the top bar for all users][4]

Now, I don't like the newfangled white theme, and some sites are going to be a agony in the donkey to do but this seems a bit hyperbolic. 


  [1]: https://i.sstatic.net/lWDdi.png
  [2]: https://xkcd.com/1172/
  [3]: https://i.sstatic.net/hqpPi.gif
  [4]: http://meta.stackoverflow.com/a/343667/674571