atc tells you why they gave you a speed restriction#1859

It would nice if we could ask the atc why they gave us a speed to maintain. I was at cruise altitude and atc told me to maintain 250kt and i coudn t find why. Having the possiblity to ask “ any reason for making us slow down herecallsign“ would be really great, of curse when in approach it is obvious that you are getting sequence so asking why would be useless.