Togekiss has base 50 Attack so in a generic case, no Extremespeed is practically useless since the most your going to do with it is finish of a Pokemon on like 5-10% health
However it does have a rare use in a mixed attacking set in Competitive which would look something like this;
Togekiss @ Life Orb
EVs: 252 Atk/ 252 SpA/ 4 Spe
-Roost/Aura Sphere/ Drain Punch
Hustle increases Togekiss's physical capabilities by 50% to it becomes a viable mixed attacker with work up, though at the cost of accuracy.