We all know that since time untold the Mma frontend uses an incorrect DPI setting for rendering fonts. As a consequence, while there must be literally hundreds of thousands of Windows (or Mac) applications that will render, say, a 12-point font as a 12-point font, the Mma frontend renders the font as a 9-point font.
What is worse, there is no good way to fix the issue as a user. Sure, I can set the magnification globally to 1.33, with the result that any graphics in the Mma documentation will look bad, and need to be regenerated to render properly. Or, I could set the ScreenResolution parameter in Formatting Options->Font Options->FontProperties to "Automatic" (which indeed would be the right thing to do), but, oh joy, now I will have text labels cut off in various palettes. Oh, and let's not even get started about the fact that, since various frontend dialogs (such as, e.g., MathematicaClosingDialog.nb) are using fixed-size windows, your menu bar may be wrapped into a second line if you dare to customize your Windows menu fonts. Well, at least that's not an issue in Windows 10, since Microsoft doesn't allow you to customize those fonts anymore, but I digress...
In brief, the Mathematica frontend is a disgrace, which is all the more disappointing given the potential it could have, and given the fact that this would be so easy to fix for Wolfram. All they would have to do is set FontProperties to "Automatic" by default, and then adjust all of the built-in palettes and Help notebooks to format and render properly at the resulting size. Why in all the world Wolfram refuses to do this is beyond me.