I work at an LBS that caters to the road market, and frankly I'm struggling to think of any failed 10-speed brifters over this last season.

OK, there were two or three left-hand 5600-series brifters that conked out when used on doubles (they were triple-capable), but Shimano covered them under warranty and has now split 105 into dedicated double & triple left-side brifters.

On the right side, it's the 9-speed ones I've seen have the most issues (sometimes precipitated by the loss of the small bolt visible on the rear of the lever blade, as in attached pic).

If you want to address a really prevalent product-failure issue, offer a rebuild service for cracking Bontrager paired-spoke wheels