Leaflet maintainer here. There is some work on a rotation code branch, plus I've been working on something called "Leaflet.GL" to do WebGL rendering. The OL3 folks just have more time and resources, you know. Also Leaflet must still work with IE8 (OL3 doesn't, there are some cases where that's needed).

We have a friendly relationship with the OL3 folks, even though sometimes we're jealous of their WebGL rendering, and sometimes they're jealous of our lower learning curve.