construct classic and multimedia fusion are both more powerful than anything flash can spit out - compare scirra's and clickteam's team sizes to adobe's.
Adobe makes some great tools, but flash really isn't one of them. I honestly don't know why flash is so far behind, but my guess is that because they dominate the market, they just sat there idling, just like internet explorer was before firefox showed up - the browser wars are in part responsible for the surge of html5 content: competition stimulates innovation. No competition = no innovation = a product riddled with bugs, with poor performance, and slow feature release cycle.