Help me understand ISO settings

Hi - dumb question time.....

I've been reading reviews of the D600 and see that the performance at high ISO is fantastic.

According to Ken Rockwell "Resolution and noise have almost nothing to do with real image quality"

So my question is - why would you set a good camera like this at a low ISO if the quality is no different - why wouldn't you always use a high ISO ?

I assume Ken R is talking nonsense and you really DO get better quality photos at low ISO.

??