An anecdote that you can extrapolate at will. I remember a while back my dad (an EVP at a large chemical company, not exactly bleeding edge IT considering they had Windows 2000 after Vista was out) was astounded to find out YouTube was blocked for most of the employees, but not for him. They started posting instructional videos on YouTube and he only found out because his marketing guys couldn't open the videos they had created. The ban was gone within an hour, after it had been in place for who knows how long.
Enough websites break and you get the executives calling their IT guys saying "why doesn't this work for me, I need a new computer" and eventually things will get changed. In the meantime, a lot of IT departments hunker down and don't want to change anything because people ALWAYS complain when there is change.
Simple truism of office politics - if it is the executives idea it is "great", if it is the IT department's idea, it "sucks", regardless of technical merit.
It seems to me a both an admission of defeat by management and a statement of distrust of employees when it is done.
Though it really depends on your market as their final pie chart shows. I know our stats show that IE6 barely gets a look in so we have dumped supporting it as the hassle was too great.