I agree, and I also point to the Halo story for the same thing. When 343 took over for Halo 4, they decided to not only define the Forerunner species, but showed them AND had us "fight" against one as the final boss.
The original concept of the Forerunners was that they were merely ancient humans, but not everybody at Bungie could agree on this nor whether they should even continue dropping more hints about the species. Many of them also agreed it was a good idea to never show the Forerunners.
The mystery surrounding a race is a crucial point at keeping things entertaining.
Like we didn't need an explanation for either of these things. The fact that Yogg's blood was special could literally have just been "Cuz he's an Old God"
The fact that the Old Gods existed could have just been "They exist" which is when I always thought they were interesting.
I think that's a concept that strongly rooted in Lovecraftian nightmares where things just exist outside of the mortal comprehension, so the logic by which they can exist simply couldn't be comprehended even if they directly told us.
I think that's the best way to explain these kinds of things in stories, especially with the Old Gods.