Not this old chestnut again!!! We do much the same at Heathrow - it's to provide tight spacing on final approach to achieve the high landing rates demanded by the airlines. At Heathrow we are aware that some British Midland 737s prefer 170 kts to 4DME and we try to accommodate them as often as possible. Occasionally a BA 73 will ask for 170 and we try to help out.. However, we have no specific instructions as to which aircraft would prefer a different speed and most pilots are happy to accept what we ask for. Two points here - first to those who think it's too fast.. you should see the speeds they fly when there's no other traffic! To those who think it's too slow.. I put a "no speed control" on a 737 a few days ago and he reduced so much on final approcah that we had a go around!
You can't please all of the pilots all of the time and 160kts seems acceptable to most!