@scamp: I don’t think life is that short. Even if you are as extremely bothered by all-caps writing as possible (sighing with frustration, ~3 seconds; complaining to your coworker about the idiot that did it, ~15 seconds; posting a fluther thread to ask about it, ~2 minutes; reading responses to the fluther thread, ~10 minutes), it only amounts to about 12 minutes and 18 seconds of your life.
The current world average life expectancy is 66.12 years (that’s including the very low life expectancies in third-world countries, where people don’t even have the internet and couldn’t possibly be concerned with all-caps writing, as well as those who die as infants and also couldn’t possibly be concerned with all-caps writing), and even using this very low-balled life expectancy average, the amount of time spent being bothered by all-caps writing accounts for only 0.0002123578% (exactly) of a lifespan, so I think it is okay to do.