Ease of deployment/integration is the crucial issue, of course. The Javascript+DOM+xmlhtmlrequest model is just so horrendously, hackishly chicken-wired I'm always ashamed to even touch it...much less use it professionally. Flash and java applets from day ONE were superior in every, single way...utterly superior...except when it comes to deployment/integration. Java applets have the habit of seizing up the machine and mysteriously failing to load...flash is a bit better, but is gradually turning into this decade's popup launcher. Neither work well with webpages. Their failure to really become platforms just shows that an extra second or two of wait time can be a competitive killer.

But, if MSFT can do this right, goodbye javascript.