[ahoge]

For one, it's written in TypeScript. There is one codebase for ES5/6, TypeScript, and Dart. A big benefit of Angular 2 is the better tooling you get with TypeScript and Dart.

It uses things like classes, decorators, and the <template> tag. It uses a virtual DOM, which is still a fairly new concept. It can run in Web Workers and you can even use it for native applications which do not have a regular DOM.

It really is quite different from anything one could have started back in 2009. Even those odd-looking attribute might have not worked because HTML5, which specified a lot of those things more precisely, was far from being done.

Angular 1.x made pretty good use of the things which were available at the time.