While a donkey running at the same speed as a horse wouldn't make any sense, an actual improvement to donkeys would increasing their speed while overburdened since packing a lot are what donkeys are supposed to be good for.
If we get the long awaited trading overhaul in paralel with my suggestion this would both revive active trading and donkey riding.
Vanilla Archeage got the donkey features right by making them superior to horses when transporting trade goods.
Personally I miss launch days when a good part of the playerbase was using donkeys to travel around Balenos and Serendia.
Bring back the wings!! you put them in for the event and then took them out! why? donkey wings made playing on shai immersive and fun! <3