If some folks misread the instructions before assembling a chair, and they build the chair wrong... the solution is to end the chair's entire product line, for everyone?
If the instructions are vague to the point that there have been ream's worth of articles and essays written over the decades on making them clearer and more useful, but many of those articles are contradictory or don't work well with each other, and there are many, many other ways to produce chairs that just as good... yes, maybe you need to toss that one chair.
The mistake is in reading the alignment listing as stating it's the race itself that's inherently "always" or "often" evil, rather than the default culture as presented in the book. This is something they could have (should have) clarified, without eliminating alignment completely.
Like I said above, you're writing your own way to make alignment work. There may be a bit in the MM that states "this is default" (which by the way, means
automatic setting, meaning that unless you actively change it, all whatevers are that alignment). Also, saying it's an evil
culture isn't better than saying that all the members of that culture are evil.
Let's say you have a culture that lives in this particular area. Quick, is that culture evil, good, or neutral in their cultural practices and ways that they deal with other cultures.
Now let's say it's a culture of hobgoblins... is that culture evil, good, or neutral? I bet you automatically went for evil, because that's the default.
As noted, this could also be improved by having multiple default cultures, or explaining more clearly when the one listed is merely an example, not a fundamental characteristic. Instead, they went for the superficial "fix", without actually addressing the issue.
Yes, it could be improved that way. However, that has
exactly the same result as if you remove alignment.
Yes, some folks want to play D&D like a video game, with just enough behavior to guide the monster's "AI". And there's nothing wrong with that. Simple "beer and pretzels" gaming is as legitimate as deep, story-focused gaming.
So why not have the bad guys be mindless automatons like constructs, zombies, or skeletons; undead creatures where the taint of negative energy or hatred of the living has completely and irrevocably overwhelmed any mortal mindset they might once have had, like ghouls, wights, or wraiths; creatures made of pure, distilled evil like fiends; creatures that inherently inimical to life, like mind flayers (who reproduce by parasitically taking over other creature's bodies against their will); or creatures that have been transformed into something dangerously violent and can't be cured, like lycanthropes or sea spawn? (And that's not including things like slavers, bandits, raiders, or puppy-sacrificing cultists.)
There's plenty of bad guys that can be killed without a second thought or moral implication even if you remove alignments.
If they give monsters default behaviors of any stripe, isn't that biological essentialism? When we say a sapphire dragon is warlike, isn't that essentialism?
Not in the same way, because there's no morality arbitrarily attached to that description. A warlike creature can fight because it loves bloodshed, or because it wants to see great tyrannies ended, or because someone paid it. "Warlike" can also be interpreted in other ways: in 3x, sapphire dragons were described as loving to
talk about military history and tactics--you can play one as a historian, a professor, or even as a wargamer (Wormy lives!) if you wanted.