Why was Bitshares 2.0 changed to have forced settlement?

[yvv]

Forced settlement maintains the peg of bitAssets from below. Market price could go significantly below the peg price without it.

[Bitcoinfan]

I've forgotten why forced settlement was instituted in Bitshares 2.0.  Does anyone remember?  I recall that Bitshares 1.0 wasn't working because of the lack of short liquidity and for this reason force settlement was put in?  Or was there not enough buyers of Bitusd to guarantee a peg?