Actually you wont be able to farm the +2 shards after 3.1, as you can only have 32 shards - with the patch they'll maximize number of shards.
Source
It does not solve any problem, it just speeds up shard generation (most of which you got on trash anyway).
It can serve as a bandaid - but shard stacking could have served that purpose aswell...
I can hardly imagine that on progress raids (especially demo/destro locks) will switch to DS when wipe is imminent... Or the purple rays will become a new "it's-a-wipe-abandon-ship" signal.