Nearly all volume controls suck because by and large the software world is ignorant of the fact that loudness scales logarithmically. 99.9% of volume controls scale the output linearly.
Wrong. Windows's volume output is the percentage squared, and Linux PulseAudio's volume output is the percentage cubed. Nonetheless I would prefer that the volume output was exponential (2^(slider position / constant)). This way, pressing the "volume up" key 3 times always increases the volume by a constant factor, regardless if you're on loud or quiet speaker/headphones. Additionally, on loud headphones, you won't have to fine-tune the volume in the very bottom of the slider (eg. 1 is too quiet, 2 is a bit loud, 3 is painfully loud).
On Windows, I hide the default volume control and instead use Volume2[1] set to exponential mode. On Linux, I haven't found a good solution for getting PulseAudio to use exponential volumes.