I don't mind them for kiosks. Really, what alternate form of control could you have that's cleaner? In fact, buttons and other controls with crevices collect all sorts of stuff, but at least a screen could be wiped periodically.
The world's a disgusting place no matter what you do. We're constantly oozing bacteria, viruses, hormones, and sweat that all over each other nonstop. Invariably, you're injesting fecal matter and bugs and... let's just say, touchscreens are the least of our problems.