Who is this we you speak of? You can drop support for IE8 any time you want. I'd rather not drop support for the latest version of Opera though, which I've had to do simple because it doesn't have flexbox.
How can you say you can drop support for IE8? Its still hugely popular (13+% of market). While I love opera (my daily browser but only 2% of market) I could see dropping support for Opera before IE8, until IE8 loses more market share.
Simple, I don't live in a world where the target audience for every site I write is 100% of available web users. Some projects are directed at corporate users with IE8, some are directed at mobile browsers.