No configurability

Even left+right middle-click emulation isn't good enough for some work. I configured the non-Lenovos using their keyboards to emulate the missing button(s). I even bind a key to left-click with the keyboard on the Mac because clicking on the trackpad causes a small jog in the pointer position.

I also threw in a few other cases where inadequate configurability ruins the end-user hardware experience. Most of these are Synaptics devices, which seemed worth talking about because the OP really seems to have a hate on for those.