Trackpads have a major issue. They are not accurate. If you heighten the sensitivity, they have severe z-axis problems (worse than any mouse) and decreasing the sensitivity makes motions slower and less responsive. Because of the size of the target (the human finger) there is no definitive "this is where I am".

Several other of their ideas are in error. Larger trackballs are not needed (logitech and kesington both make popular trackballs with small radii that perform well. The weight of the ball is also a red herring as it is possible to make lighter balls if needed.

The "issue" of cleaning is minimal and a non-issue overall (ask any trackball user). The idea that circuit space is constrained is also a non-issue. Modern trackballs use a laser to read the ball (a feature of trackballs is no z-axis movement) The circuitry to deal with this is small as is the circuitry for much of the rest of the device.

The real argument is that the material cost is higher, so they'd rather use inferior design and bump up profit margins. Most gamers will pay over $50 for a mouse (with some of us giving over $100 for our mice or trackballs). I'd rather have a quality device and pay a little more.

What do you mean by z-axis movement?

Have you used a Steam Controller?