I still get funny looks in this part of the world for carrying a windshirt. "THAT'S what a rainjacket is for" my friends inform me. But they are carrying 800+ gram totally indestructible rainjackets that can handle the off-trail abuse we so often encounter. I like the lighter and more breathable feel of DriDucks and eVent (who wouldn't), but the current lightweight offerings are just not up to this kind of abuse. At Xmas I took my DriDucks on what was supposed to be a well-groomed track, only to find that a windstorm had turned it into a bush-bash of the most epic kind. Sadly it also rained the whole week, so my DriDucks got shredded. Still, I'm glad I didn't take the eVent jacket as that would have been a lot more expensive trip! Bottom line, when it's not raining, is that I'm both more comfortable in a windshirt, and less likely to ruin expensive raingear if I wear the windshirt in heavy bush. This is just another factor to consider into the equation, and would probably not be a concern at all if hiking in, say, the Sierras or other open areas.
Yup, we each pick our own poison, but these forums are great for helping make that a more informed choice.