@Riot, what was the intended use of Ashe's passive?

Free crits. Ashe has always been an opportunistic champion. You press R and follow up with a nice, fat, juicy crit right to their face and a W to follow up with that. It also gives her the ability to poke much like Cait's passive. When you time your AA's on minions and play a little less 'push' style and a little more 'last hit' style, you can toss out crits incredibly often and with the current IE/Shiv rush style, she's able to unleash hell in a lane when played properly. In a team fight, it's just for a quick burst though.

Skirmishes, great for going from one fight to another.