The controls do get small, though, everything is small, as Adobe does not seem to have put any effort into supporting High DPI displays yet.
Lightroom 5 fully supports HiDPI Retina displays, and on Windows it has a 200% UI font scaling option. Most of the CC products are in the same state. Windows rendering isn't as good as OS X Retina, because it has a number of issues with HiDPI scaling that Adobe are working closely with Microsoft to address. It will be a while before we get feature parity.
A 200% scale would be too large, though...at least, on anything less than a true 4k screen. Windows supports multiple scaling (i.e. 125%, 150%, 200%, and even higher than that for future high DPI displays), and Windows 8.1 is now actually capable of scaling dynamically depending on the display for multi-headed systems. Adobe should really integrate properly with Windows so that if, for example, I wanted to pull off a loupe onto a second screen that has a different DPI, it would use the Windows 8.1 scaling, rather than use some fixed built-in scaling that is independent of the OS.
If your trying to force the OS to conform to the Adobe-custom DPI approach, that's the wrong solution. Your forever going to be working against the Microsoft grain. Reference and use the OS DPI/scaling factor, and properly adjust the DPI used to render windows that are pulled off onto different screens, so that we Windows users can comfortably use multiple screens with different DPIs as we please.
At the moment, I believe Windows supports the following scales: