And this is how it should be. I want users to get tired of installing more plugins. I want them to roll their eyes when a site says "you need to do add $x to be able to use this site." We had the same problems with mp3's, and we won out. I see no reason we can't win out with any other media.
Only if you ignore:
* Users "rolling their eyes" means nothing when they'll gladly click OK to dismiss all the security warnings and installations of n plugins so they can watch Netflix. They'll complain, but the plugin will still be installed at the end of the day. I'd rather that plugin be sandboxed.
* That the practical implications of lessened security are more real, hence important than the theoretical concerns by a sandboxed plugin who's entire mission in life is stopping you from recording a fscking video stream.
The user you're talking about, the one who signs up for Netflix, gets prompted to download a plugin, shakes their head sadly and cancels their subscription because DRM is evil, doesn't exist outside of FSF patrons.
Furthermore, you imply a level of informal cooperation between the browser vendors that doesn't exist. It turns into a game of prisoners dilemma, where the first person to defect gets to claim a massive feature that none of the others do, and the others are left in worse shape.
I'm no fan of DRM, but again, it's the world we live in.