Given that power correlates to vO2, and in running it’s easy to run by feel or pace depending on course and conditions, what’s the gain in having a power meter? In cycling it’s obvious. What is it in running? I can go to a track and do intervals off pace perfectly. And in a race I am RACING, not trying to hit some power number. If I need to cover a surge, I will cover the surge if I feel I can. Or I can sit on a certain power and lose contact? WTF, no way.
The most common benefit people seem have found from running power is using it as a pacing tool in longer events. That is especially true in hilly races, but even in flat ones it can be helpful to have a real time, stable, and accurate indicator of your effort, something that, e.g., ordinary footpods or (worse) GPS often fail to provide.