Should I Leave It Out?

Hello, I just was wondering whether or not to include a scene I'd envisioned in my current story project, as it may or may not take away from the one of the tale's aspects. To explain:

One of the background plots is that the goddess who created the world has either abandoned it or simply left for an extended period of time, which has resulted in absolute chaos during the millennia she's been gone. It's gotten to the point where no one even remembers her name or anything else about her, save that she may or may not have existed.

In the scene I'm debating, the Big Bad has died after losing its conflict with the heroes, only to find itself face to face with her. It rants about its motivation and her failure to intervene in its plight—it was a spirit magically created as a servant and the point of its "evil" scheme is to gain freedom and a true physical body. She condemns it for the thousands of lives ruined and destroyed during its manipulations and atrocities and then absorbs it, much to its horror.

My dilemma stems from the fact that I feel it would take away a good deal of the mystery surrounding her, and yet the problem is that not including it would take away a sense of closure for the conflict with the villain, as all the heroes (and readers) would see it vanish in a puff of smoke. It would be...anticlimactic. So I just wondered what people thought.

If you've already established the mystery of the goddess and where/why she's gone in the story, you could just have the Big Bad be vanquished and just reveal that they are now face-to-face with an extremely angry-looking goddess then "roll credits" as it were without the "Reason You Suck" Speech or rant - just the Big Bad's "oh fuck" realisation that not only did they fail, they're now subject to whatever horror the goddess has in store.

Standard-issue thing, I'll say: since the scene in question would not move the plot forward directly, what matters is whether the knowledge that the readers would gain from the scene is important for them to know. If it is, if it's something knowing which will enrich their journey through your story in whatever way, then by all means do keep it in. If it doesn't, though, then keeping it ambiguous at most is probably the way to go.