And there are other benefits, too. It'd be a quick and easy way of telling who the veterans are in-game-- as in, who should know what they're doing and who might not. Plus, our characters don't actually age, so while gear is some indication of where they're at in progression, it doesn't tell you who's been on for years and who just powerleveled to 70 in the past few months. Some common indicator of age would set a milestone for how long characters and players have been around.
Eyonix jokes about "Old School Zymm," but it's a good suggestion-- we should have some way of showing off how long both we and our characters have been around Azeroth.