I made this specifically for my online D&D sessions. I can tell you that nobody was suspicious when I replaced the standard Math.random() with this version, and all of the "I think your dice function is broken" statements all the sudden stopped happening.
As a D&D player I can see how this might be nice, but at the same time it would be frustrating to get a 20 for something stupid (passing a DC5 check) and know that it had a real effect on my chances for getting a 20 when I could actually use it (a critical attack roll).
There are times in a RPG for (a GM/DM) relying on dice for something and when not to. For some people driving appears to be like bumper cars but for most of us it isn't 8) Apply that to D&D and the player's approach to things should be used to bias or even dispense with dice.
