Even without any hacks achievements themselves are useless. The fun is when they popup or seeing if you can get certain achievements. Having an achievement has no value itself.
However, if Steam wants to implement a gamerscore type system. Go ahead. I think it's dumb, but we all know there are idiots out there who will buy a cheap game just to grab the achievements to add to their score. More games sold can't be a bad thing. Right?
Though I could see developers then implementing their achievements so they are easy to get to tempt the gamerscore whores. Which then really makes achievements meaningless