Comment by AshleysBrain

They probably won't ever support WebGL, because it conflicts with their DirectX-on-Windows strategy which they've invested huge resources in to. The security scares are just to whitewash over the real issue - people are more likely to accept security as a reason than some strategy thing. (It's actually a very clever move - everyone's talking about WebGL security rather than Microsoft's strategy, so it's working. Them be smart folk at MS!)