People keep bringing it up for the same reason that the vast majority of Bible translations use “formed” rather than “had formed”. The whole arc of the Genesis 2:18-25 passage is one of unfolding consecutive action:
- God announces his plan to make a suitable helper for the man.
- God forms the animals.
- God brings them before the man.
- The man names them, but when all is said and done, no suitable helper is yet found.
- So as the dramatic climax to all this, God creates the woman.
- And man exults.
If step 2 was “had formed” the whole flow is interrupted for little point or purpose; the singular mounting drama of creative action, first announced in step 1, is suddenly interrupted with a non-creative, barely-related sideshow from steps 2 - 4, and not really resumed until step 5. There is no reason to translate the narrative this way except over-concern with the preceding chapter - a chapter that in many other stylistic markers diverges from this chapter, so that there already are many other warning flags that the two chapters are not to be read as a fluid union.