Good question, but then, Opera is always ignored. By everyone. I guess it still has a reputation as being clumsy and geeky? It's not true in the slightest, but obviously people still work with false assumptions if they're using IE6! It's probably the same problem Linux suffers from.
BitPop is right. Companies are the most sluggish things when it comes to software updates, we still have customers with freaking NT4 servers. Even if they want to update, company policy is often in the way. Upgrading is expensive.
As to Google making that formal proclamation, it does carry some weight, if only for the massive influence Google has. They probably want to kick IE6 out for pushing their online application services (which was why they put Chrome out in the first place), which is something MS doesn't want because it's threatening them in the long run.