Innate Movement Speed tech - Sprinting

One issue many people discuss is speed. It seems that everyone agrees that the maps are large and that sometimes you need to backtrack or explore away from enemies, so I propose a new game mechanic of sprinting.

Sprinting - When you are out of combat for 5-10s (some range that could be nailed down) you start moving at 40% increased base movement speed. When you enter the presence of an enemy, stop sprinting.

I think this could resolve many people's feelings of slowness in the game while keeping the valuable stats of movement speed in the tree and on boots. You'd still need it for good, fluid gameplay against enemies; otherwise, you'd be slow in combat and still take hits easier, but this could be an idea to explore.