I think they just realized they can continue to support the old IE versions while other JS libraries advance in functionality, or they can stay competitive.
Which other libraries would those be? (I'm serious.)
There were several fairly well known libraries a couple of years ago, but as far as I can tell, jQuery won that battle decisively. It has almost 100% penetration in the projects I'm familiar with that use a general purpose JS library, and it seems to be the default for articles and blog posts I find on-line these days too.
Part of that success came from the ecosystem reaching critical mass. Many people know jQuery. Many plug-ins are available for jQuery. And the vast installed base usually means quick bug fixes even for recent browser compatibility problems.
If there is something out there that is better by a wide enough margin to justify giving up that established ecosystem, I'd love to hear about it. The ecosystem has plenty of imperfections, but I haven't come across anything yet that seems nearly comprehensive enough to displace the incumbent here.
I think jQuery 2.0 is partly a response to Zepto.js [1] -- they're both jQuery-API-compatible, and they both drop support for OldIE (Zepto drops all of IE, though [2]).
> If there is something out there that is better by a wide enough margin to justify giving up that established ecosystem, I'd love to hear about it. The ecosystem has plenty of imperfections, but I haven't come across anything yet that seems nearly comprehensive enough to displace the incumbent here.
David Mark's My Library[0] is the best DOM library available by a wide margin. It has supreme browser support, and it's "modular" with a custom builder. The code is so solid that many people have borrowed from it, including the jQuery project and myself.
I've also created a DOM library, but with a more limited feature set (it's only a few months old). See my submissions for details.
The JS community has moved beyond DOM abstraction libraries entirely. Using polyfills is now the preferred way to reach older browsers. JQuery serves a role of abstracting the stuff that polyfills can't fix, or to go all the way back to IE6 where the differences are too great to mess with on your own. Without that, there really is no reason to use JQuery at all.
To be worth shifting away from the jQuery ecosystem to something new, the latter needs a compelling advantage and it needs to not have any deal-breaking disadvantages. Nothing I've come across so far myself seems to meet both criteria.
