To be fair, so did Adobe in a lot of theirs. They did bet hard on Flash as a platform; it just wasn't a very good bet, and very little of it went into improving the actual runtime. Instead, they tried putting sugar on top (e.g. Flex) which obviously just added to the bloat. That said, some of that sugar had some interesting ideas going for them, lacking execution notwithstanding.

Obviously I agree with you, I would never build anything new with Flex, or target the Flash runtime; but that's not to say there aren't good lessons to be learned and concepts to be snatched. Hence, the "not sure if good or bad" comment – it depends on what you steal I guess.