Perhaps in your retrospective opinion, but it was good enough for every major investment bank to invest millions in, and even enough for a company like Microsoft to try and copy...
Having been sat at the table while big decisions have been made on important pieces of software for some of the worlds largest and most influential financial institutions, I can say with a fair degree of certainty that those decisions are rarely informed or reasonable.
One thing I know to be true. The corporate world is run by insecure, ill informed pretenders who fear accountability above all else. People who only make a decision when someone under them has put their neck on the line.
Flash and Flex's success in financial services was not based on merit. It was based on fear of deviating from the norm.