As Brian said, DPI doesn't actually affect how a graphic displays on a monitor. From a web perspective, the DPI just contributes to file size bloat. 72 DPI - 90 DPI is pretty much the web standard, simply because the graphics are still moderately recognizable if you have to print out a web page. Tinker pretty much explained why we recommend a larger image size for tokens. I'll make a graphic example that might make this easier to demonstrate than just writing about it. FeltZ, I'm doing a little bit of research regarding 8-bit color. My assumption is that 8-bit is being used because it keeps the file size down. When you're assembling maps in Roll20, graphic file size is definitely a limiting factor when gaming and you can hit a critical mass where a GM's or Player's browser slows down to molasses because there's just too much content being moved around on the tabletop.