Agreed, which is my main complaint: the older (non-retina) MBP was better at sustained CPU usage (at least in my experience - this is 100% anecdotal and non-scientific). Apple used to produce a machine that was suited for the things I do, but the rMBP doesn't feel as capable as the thicker, older vanilla MBP.
It makes me consider buying a Mac Mini or Mac Pro for audio work, but I can't justify the cost right now, since audio is mainly a hobby and my MBP works fine for most of what I do (multi-track recording live events with Dante).
I was drawn to the MBP when I switched in 2009 because of the build quality, the OS, and its ability to handle professional workflows, but it seems that they're abandoning that use case. My favorite machine of all time is still my '09 Core 2 Duo MBP.
The extra portability is nice, but if I wanted portability over power, I would have bought an Air (or I suppose a Macbook now).