I like your suggestion. It can be quite a pain trying to find someone, even if you have 40-50 friends all the red names look the same and it’s quite tedious to look for someone. Sorting out friends by antiquity would be a very interesting feature in my opinion. Also, I don’t know if it’s possible but you could hover over someone’s name -online or not- and tell you how long ago you added them to your friend list. Again, I doubt they have this information but it’s worth a try.