Fully open isn't the answer for everything. Flash is the most widely distributed piece of software ever - it got that way by NOT being forked and offering what HTML didn't both in terms of consistency and features.
As a side note, I think there is also a subtle common UI pattern to abuse the hover feature on websites which is common in flash. It makes touch-based browsing more difficult and I wish web developers would avoid it. It isn't fair to blame flash for it though, javascript can do it too.
Adobe and Macromedia were a startup once, just like many companies by HN members.
I want Adobe and its technologies to improve, not die.
In this particular case - the web was ugly before Flash and it'll be just as ugly after it. And as waxpraxi writes, some good did come out of it (force me and i'll make a list : )
Flash is not a gun, it does not kill, and i don't wish it to die.