Yes and no.
The WoD system is a bit more complex, non-optional (or rather, less optional), and lets you stockpile the resource.
Additionally, the PHB and DMG really undersell the system. In both books the first thing you read about the system is how you can totally ignore it and be fine. In contrast, Feats are also an optional rule, but the rules governing feats don't repeatedly mention that fact every time you look them up.
I see what you're saying. In order to really do it the same way they'd have to have more codified traits though. The archetype specific type of willpower gain conditions in WoD would require them to either limit archetypes or have players/DMs create conditions for each traits. Unless you are meaning basing that on your Background, rather than Ideal/Bonds/Flaws. Even with custom backgrounds being supported, that's actually much more doable. It would have been interesting if they had put something like that as an optional rule in XGtE. (Coming up with rules for every one sentence description of something important to a character, like the ideals/bonds/flaw are would be more difficult.)
I also agree that being able to stockpile would make the system better. That inability really throws a damper on the way the system works for my entire group. We're all resource hoarders I guess. But, on the other hand, I don't like having something as powerful as Inspiration stockpiled. The PCs don't
need any extra power boosts!
What I eventually did was come up with rules for what happens when you have Inspiration but would get more awarded to you. It turns into something I call "Impact" which
can bet stockpiled indefinitely. Impact never converts back to Inspiration though, so it doesn't mess with that mechanic. What it does let you use is buy campaign influence. You can spend certain amounts of it to request the DM include fun stuff he wasn't already intending to included in the campaign. Like this:
Vignette: A character-focused brief event or escapade - 3 Impact
Development: A character-focused enduring campaign element - 15 Impact
Scenario: A character-focused storyline with lasting importance - 37 Impact
The players don't directly take narrative control with Impact, because I don't run D&D that way. Rather they say they want to use it, and perhaps make a vaguish suggestion of what they are hoping for out of it, and then I come up with an interesting thing to do with it. It's actually not even supposed to be a pure benefit to the character--as in, it isn't intended to provide them resources or power ups. Rather it is supposed to give them a way of buying focus for their character. I try to make it so the results are as likely to be "bad" as "good", but the point of them is to add enjoyment by tying the characters to the world more dynamically.
The funny thing is that my players don't actually spend it very often (I think we've had about two each of vignettes and developments, and we've been playing since about 2016), but it does make it more meaningful to them, and they like to receive it--apparently to stockpile for buying scenarios at some point.