> so this is just another way of thumbing their nose at open standards.

It's likely much less "thumbing their nose at open standards" as it is just a matter of making sure their software works for the vast majority of their users.

I know that's how I develop software, anyways -- if there's a quirk in a browser used by a very small percentage of users that's not entirely simple to fix, I don't. It's just a matter of priorities: create new features and upgrade existing ones for 99% of your users or fix features for 1% of users. Depending on the feature, you make a rational decision.