2 years ago I was exploring frameworks for an enterprise project. I tried Batman along with most others, I can easily see why building your own framework would have been an option any earlier than that.

Most frameworks weren't even at 1.0 stable yet. I initially wrote a fairly extensive prototype with Ember, but there were breaking changes so frequently I couldn't keep up with the learning curve. In the end I chose Angular because it had the best documentation, Google dogfooding, and testing was an obvious priority. Worked out so well we're on our 4th major Angular app now.