Interesting that you mention this. The unfortunate thing about this lack of version switching is that I’ve had to resort to manually defining JUCE_OPENGL3=1 for the last.. many years.. to get OpenGL 3+ to work on Windows. (Windows & OpenGL 3 fix)
The downside is that users with ancient hardware running this software end up with a blank screen (usually old on-board Intel GPU laptops, 2010 and older). So in order to get things drawing as normal (using the software renderer), I have to query the OpenGL version and conditionally remove the juce GL context from the top-level window.
Would be nice to have that version switcher in place as OpenGL 2.1 will probably be fine for most older systems/crappy machines.