Maybe... but also maybe not.... maybe it happens more frequently than you think but because the screen is naturally resilient to these impacts you don't see it.... until one hits it really hard and cracks the screen.A carom of a large rock off the faceshield into the TFT seems like such a freak occurrence. I'm not inclined to protect myself against something that rare. While the glass cover is pretty, it also appears to have some glare that the native plastic doesn't.
BTW, the native TFT surface cleans up really well to new form. I wash the bike every week or two and use a soapy sponge on the TFT and a lint-free drying cloth. I then use Plexus to super smooth/shine it up.
The screen protector does seem to add some glare, but you only notice it when it is off. Under bright light the screen is plenty visible. Plus I don't really look at the screen much when riding anyways. Just looking for the flashy light