Tbh, in the beginning you had fatigue, but actually this seems the only valid point speaking for a new resource (still could be done without revamping the whole thing, imo, but if they fix a few things this way, it is good).
Problem i see is just like Mayn said: the seconds. This sounds like they will not change the percentage drain and linear regen approach.
So instead of making a fairer system based on mass, acceleration and energy (the formulas for that are already in many books) they keep the pseudo-approach probably.
But i think timing might be a good thing, because timing means skill. Imo there is no skill involved just to grind best gear and pop best potions.
Timing doesnt always mean skill.
Timing on sprinting system would simply mean you have the opportunity of avoiding 1 out of 10 attacks. While having no timing on sprinting and instead an apple ammount of it means you have the opportunity to avoid 10 out of 10 attacks.
Timing in this doesnt increase skill, it only makes it so good players have a smaller gap of power compared to bad players. Its dumping down the game so its easier for noobs.
If you mean timing as in "fixed duration or with cooldown once triggered", you have a point and i would agree. Otherwise not. Choosing when to sprint and when not is what comes with experience or skill, pressing shiftlock isn't.