Bach in the earlier days of Diablo 3 everyone wanted a say where you would be rewarded for playing a run through with no skill swapping. And NV was the result.
If this was the case this is a bad form of doing it. Check this idea.
Imagine if Nephalem Valor was no longer an ability for elite packs. Instead it gave you stacks of NV when you killed quest bosses, proper bosses.
This would make the bosses substantially more attractive to kill, and for each stack the next boss would drop even more. This would make it attractive to run acts.
There is a distinct nothingness when you kill bosses in the current D3, they used to drop very well in earlier Diablos. This would help build gradually increasing drops for these bosses, as the reward for playing a longer game. It would not reset between acts,
Keywardens require at least 1 stack before they drop their keys.
Stuff like that, i just feel this NV valor is a hassle big time, its kinda cool in a way, but we dont really need it and it requires your attention.