Most people just don't care about their input devices, even though many of them have health issues. For example my dad has tennis elbow, and I've more or less forced him to try an ergonomic keyboard (after trying MS Natural Keyboard, some split Chicony and Goldtouch, I gave him an MS Natural Keyboard Elite, and he seems quite happy with it).
There aren't many choices either. If you're not willing to spend more than $50, there are only MS Natural Keyboard and its clones. Goldtouch, Kinesis FreeStyle and TypeMatrix are not exactly cheap at about $100; with TypeMatrix, you have to almost relearn how to touch type. If you want a mechanical, you're left alone with Kinesis Advantage and Truly Ergonomic (and Maltron or some rare vintage stuff).