It’s a cosmetic issue.
The image probably looks huge on your screen if you don’t have a retina, so I included a downscaled comparison on how it looks on my screen if yours behaved like that. (the right image roughly has the resolution where 1 software pixels represents 4 pixels on your screen.)
Of course it doesn’t look as nearly as awful, but your eyes get spoiled and non-HiDPI elements start to bug you. In reality it looks just as good as on a normal 15" macbook. (I compared next to one another with my old MBP and the difference is non-existent, they look equally good while running Max, or when I run 1440*900 nonHiDPI)
So the whole retina thing is 200% upscaled GUI, so everything looks ultrasharp. Considering max obviously uses vectors (because you can zoom-in and resize objects without losing any clarity) the update shouldn’t be such a huge problem.