what makes a d&d sub race stick?

[KorvinStarmast]

this has made me ask myself what makes some options stick and others not.

Depends on the playing audience.

Each time they start over with a new edition, they are replacing dozens of books with just a few. Some content will not (yet) be included.

Kind of like a medically administered enema to the bowels of the game.

By contrast, men (eventually re-named humans), dwarves, elves, and hobbits (eventually re-named halflings) have been in D&D since the first three-pamphlet edition, because players who had never seen D&D wanted to play them.

And, sadly, EGG gave in to the temptation to put hobbits into the original game.

While a lot of content has been invented just for D&D, playing in fantasy worlds like the ones we've read has always been a major draw for a lot of people.

Looks like you hit the bullseye with that one.

D&D has a long history of throwing subraces at a wall and seeing which random features stick.

Tieflings didn't always have horns. The drow as PCs was an unfortunate mistake, but let's give RA Salvatore credit: he made it stick.

The Kender are an example of a non-sticky subrace (treating them as a subrace of gnomes). I think most of it comes down to their chaotic nature which rubs many other players up the wrong way as a lot of Kender players turn up the chaos to 11.

Honestly, there isn't a need for subraces.

The problem with Kenders isn't that they're chaotic, it's that they're annoying, have a compulsion to do something that is considered a no-no for many players, and the authors pretended they were Perfect(TM) in spite of that. They were presented as unable to stop themselves from stealing from everyone, but it was supposed to be ok because they were Innocent and Quirky.

And that they are the product of bad writing/creating by Weiss and Hickman - which is too bad since a lot of what they did with Dragonlance I liked.
(I'll not go into my usual rant about Kender...)