I think it's great. No one is forcing anyone to upgrade, jQuery 1.9 is stable and you can use it forever even with new browsers. So what if it's not supported after some unknown date in the future. It's solid and will keep on working. No one is forcing developers to switch, but in my case I don't want my users using older versions of IE. We develop apps for in-house use, and breaking old insecure browsers is a good thing, it promotes user upgrades. A smaller jQuery is great, as it will reduce load times a bit. I couldn't be happier with the decision.