Viscoelastic properties are critical for the optimal expression of speed. Viscous materials, like a pool of mud or Jell-O (you may have wrestled in there in the 80's) absorb energy. Elastic materials, like a steel rod transfer energy.
Sprinting, or any speed output, requires Pulsatile Athletic Stiffness. This means that we need to be able to quickly turn on stiffness like a steel rod (when transferring energy into the ground) and then relax the appropriate muscles when that energy returns so we are not driving with the brakes on (contracting when we are supposed to be relaxing).
I think many folks have a misunderstanding of this viscoelastic property. They have been led to believe (perhaps no fault of their own) that being viscoelastic is being like a wet noodle. That's only half of the equation. It's the transitory stiffening that's key. Stiffness gets a bad rap because almost everyone equates this with feeling globally stiff and lacking movement variability. That's bad. But athletic stiffness is good...where and when we need it. Watch any sprint race and you'll see beautiful viscoelsticity in the competitors.