This was a shakedown by the CFTC. The CFTC "decided" that bitcoin was a commodity and that it falls under their jurisdiction.

I asked Bitfinex on reddit about what specific changes were made here: https://www.reddit.com/r/Bitcoin/comments/4m8tfs/cftc_orders_bitcoin_exchange_bitfinex_to_pay/d3ts39e

This was Bitfinex's reply: https://www.reddit.com/r/Bitcoin/comments/4m8tfs/cftc_orders_bitcoin_exchange_bitfinex_to_pay/d3tsgik

Go figure!