I'm curious as to why this isn't an acceptable reason for you? Seems to me no different than sticking to an older version of anything else. Star Wars without expanded universe, board games without expansions, vintage cars, etc. It's generally done because people prefer a certain type of experience (either in general or for that particular instance) which is better represented by sticking with an older version.
I'm not sure I like the phrasing "isn't an acceptable reason", but it is a bit beside the point. To break down my statement here's the full version for my reference.
I've said it a few times, my biggest problem is with auto-bans that are in place simply because the DM can't accept a certain race since they didn't exist in the 2e version of the game or because a few players have played stupidly and happened to choose that race.
So my personal biggest problem with this debate is auto-bans. This, for me, is when someone states that for now and forever these things are banned at my table, typically as per this debate I am talking about races or classes. That is the core statement, my problem is with people who said 5 years ago X, Y and Z will never be played at my table.
I then included two of the most common reasons I have seen that auto-ban that have led me to think this is a problem. One is "Well, it wasn't in version X of the game, so I don't allow it". Sure, some people like classic cars, but this is more (to me) like someone who refuses to play anything other than disco on the radio during a long car ride. You have a taste, you enjoy what you enjoy, but other people have different tastes and banning everything you don't like doesn't seem right to me.
The second example is "I'll never allow drow, because they are all Driz'zt clones" or "I'll never allow Tieflings because everyone who wants to play a Tiefling just wants to be an emo-goth and I won't stand for it". The assumption that a race can and will only ever be played by one type of person for one type of reason... well, the variety of DnD characters itself tells me this isn't true and therefore seems to be a bad reason, perhaps based on real experience, but a bad reason.
And, needing to prove myself to you before I can play the character I want to play, while I understand the logic behind the idea, is wrong. Even if you think my character is ridiculous that doesn't mean I shouldn't have a chance to play it. After all, just because I can play a human paladin to your satisfaction doesn't mean you'll think I can play a Tiefling Thief.
Now, I understand banning thigs for world building or thematic reasons, even if I don't neccesarily agree with it, but this thought just came to me. How often do you hear about someone banning High Elves, because the low magic setting doesn't have room for a race that has auto-cantrips? Elf, Dwarf, Human, and Halfling are almost never banned like Dragonborn, Tiefling or Genasi are, because people see them as core and the others as "that weird stuff for little kids" (A phrasing I have heard before even if no one here is advocating that)