Not to diminish your point, but calling Flex the first RIA technology is a stretch of imagination.
Even if you ignore all the other technologies that were labeled RIA, you simply can't ignore OpenLaszlo which happened before Flex and from which Adobe probably took inspiration:
Yes, OpenLaszlo did come before FLEX, and Macromedia was certainly aware of it when they designed FLEX. The big difference between OpenLaszlo and FLEX is that OpenLaszlo was designed from the start (2000-2001) to be independent of the delivery platform, and FLEX was designed from the start (2003-2004) to lock developers into Flash.
OpenLaszlo was originally designed to be cross platform, first targeting Flash, then eventually other platforms like DHTML, which it now does. But FLEX is impossible to use with anything but Flash, by design.
And now, predictably, people are complaining about being locked into Flash because they used FLEX, while Adobe is abandoning FLEX and Flash.
Even if you ignore all the other technologies that were labeled RIA, you simply can't ignore OpenLaszlo which happened before Flex and from which Adobe probably took inspiration:
http://en.wikipedia.org/wiki/OpenLaszlo
http://openlaszlo.org/