[firefoxman1]

'cuz jQuery is sooo 2006.

A more serious answer: jQuery normalizes JS quirks across browsers into a unified interface, plus it provides a lot of goodies.

What jQuery isn't good for is organizing code. That's why Backbone and the term MVC have become popular lately. Applications need to be organized into something better than a big sloppy helping of jQuery callbacks.

Enyo allows you to build modular, organized code in a somewhat familiar way. I'd say it's in-between a big mash of jQuery and a full-blown MVC framework. If you want to think of it in an MVC way, it's like combining views into controller code...and I don't know where "models" fit in. And unlike Backbone, it provides its own built-in DOM manipulation and, as of today, a UI framework too.