I’ve had a rather unpleasant history with mouse use, culminating in the inability to use a bog standard mouse with either hand for more than 2-3 minutes before the onset of severe pain. This reaction has built up over many years of mouse (ab)usage, and I have a certain loathing for the devices now. It has to be said that many of the cheaper mice (normally the ones shipped by certain PC manufacturers) are some of the most unergonomic pieces of equipment available. Computer manufacturers have a lot to answer for having shipped us less than ergonomic mice with their computers for the last 20 years. Quite often an end user does not experience any other type of mouse apart from the one that ships with their computer system. Whilst these mice are designed with aesthetically pleasing features, their ergonomic qualities leave a lot to be desired. This can of course be tolerable if the user seldom uses the computer, but if they do use it a lot then it can ultimately lead to the onset of RSI type symptoms.
Having seen what manufacturers ship with their systems, I would be a proponent of legislation to ensure that the basic minimum mouse is an ergonomic one.