I fly 737-800 280 in descent.
250 is way to slow if you ask me. Or we al should do it or nobody. It is not gonna work if you plan for a 280 knot descent and you have to slow down at FL250 already to 250, You will get above your descent path and maybe have to use speedbrake because 1 clown is doing 250! In my example all 5 planes had to slow down and the whole arrival flow was being screwed up and everybody was complaining!
I think that again either we all do it or nobody does it untill then fly 280 thats what most airlines do!