In a -700 160kts is possible at most weights with Flap 5. It can get a little 'slippery' though and Flap 10 is a little more comfortable.
If it was vvv cloudy the other night, ie: requiring a Cat 3 approach, then good airmanship would suggest a more academic approach and thus lowering the gear a little earlier than usual.
It just helps to get a nice stable approach very early on to give you less to think about in the latter stages.
Of course, ATC might have asked for 'min approach speed' in order to get another aircraft off the ground.