I think this is an ok idea. It'd be better if the user could download whatever driver they think works best for their system rather than just downloading the latest drivers. My experience with the latest available drivers from AMD have been horrid after 10.5.
Correct but that's not the point, its the fact that you no longer have to google the date for the next Cat. update as Steam will automatically inform you the day that it comes available and you auto-install it right from Steam. This update leans towards Steam users that have Radeon cards, it's not a technological breakthrough but at least it's a step in the right direction for us gamers. You can also express your thoughts in the Steam forums where a new AMD/Driver section will be implemented, this will help create better future drivers.
Cat 10.3 might be the best driver for your system, on my side it screws everything up so in all it depends from system to system as opposed to NV drivers which normally are trouble free regardless of the system.
i think most people are fine with or without this feature added to steam. and i know some people wouldn't care their graphic card running older driver as long as they don't have problems with games even though they knew new driver is out. as long as this feature will not automatically update your drivers then it's fine