With very few exceptions, I pinch my barbs while I tie. Fish sometimes throw barbed hooks, too, and the fact it's so much easier to remove barbless hooks from both fish and anglers makes it a no brainer for me. It's when I buy flies that I sometimes forget. The ordeal of trying to remove a small, barbed nymph from a hooked fish (or worse, a fishing buddy) is a solid reminder.
In the conservation age, anything we can do to limit harm is a good idea. Pinch your barbs, wet your hands before handling fish, don't let fish flop around on the bank if you can avoid it... all small things we can do that could add up to a big difference.