Why ionic 3.0.0 beta started right after ionic 2

it not been 2 months since the stable ionic 2 and ionic people are starting to develop ionic 3.o beta instead of improving ionic 2 more and more for some time.
is ionic 2 a failure or something?

After ionic 1 stable release there was a long gap for ionic 2 but why not this time???

I would say primarily because compared to the chasm of difference between Angular 1 and Angular 2, the gap between Angular 2 and 4 is but a tiny leap.

Ionic 3 is about migrating to Angular 4 under the hood. The syntax remains the same, so it is not the quantum leap that we had with Ionic 1 to Ionic 2.

In the future, the version number will fade away and we will just call it Ionic. Much like Angular has changed its naming flow, Ionic is following suit.