I definitely agree with the point of the black goo being more dangerous than the Alien, and therefore kinda sidelining it.
But honestly I never had a problem with it otherwise. It's definitely used as a convenience item for writers a lot. But I forgive it, for the possibilities it adds, and expansion to the xeno/alien roster that it provides. I'm talking more so the creatures rather than the zombies (not really a fan of the Fifield zombie, other than the alternate version where they make him look slighty xeno-like, with the longer head). I personally always felt that the expansion on the xenomorph felt pretty stagnant. People either just made the same old drone/runner/warrior, or just made a xenomorph with slightly different traits of animals it spawned from, or just made them the same old design but a different color (they're xenos, but RED. how creative).
So I really appreciate the additions to the roster that the black goo has provided with the trilobite, hammerpede, deacon, neomorph, etc. And overall I feel that it offers more opportunities for creature diversity apart from the classic xenomorph lifecycle. Which is something I've personally always wanted to see in the series.
Not saying it's a perfect plot-device, but I've mostly enjoyed what it's provided to the series.