I'm starting to wonder if it doesn't have merrit. I have read several fatigue related posts and articles now that have comments that recommended replacement schedule are out there. Probably enough failed that making that recommendation is a legal maneuver.

This thread says "Felt" recomends the 2 year replacement on Aluminum handle bars.
http://www.bikeforums.net/showthread...pped-handlebar

I have heard this for carbon as well.
Looked up Cannondales main manual that comes with every bike and they go in great depth about inspection for fatigue and lifespan. They don't give a replacement schedule alluding to that being how the bike is used but they do make a point of saying light weight components do have a lifespan and what to look for and making regular inspections.

Looked at Felts site trying to find where Felt says 2 years on bars that was posted in the handle bar link. Cound not find that but it may be in the manual for the bikes and you have to e-mail a request for them. They however do have a life-cycle clause in their warranty page along the lines of Cannondales. http://www.feltbicycles.com/USA/Support/Warranty.aspx

After reading a few of these sites I think it is very possible a manufacture has made a blanket statement to replace at "X" years as a legal maneuver from the very high possibility that an owner does not do reasonable maintenance and inspection on their bike. Most seem to go with "Owners responsibility to frequently inspect for signs of damage and fatigue". Again it would be very hard to win against either argument in a court of law once you have cleared the warranty period. You would hope in a fair and just world it would be owners responsibility if there is not a proven defect but people have managed to win multimillion dollar lawsuits being burned by "HOT" coffee.