Elves. Why'd it Have to be Elves?

In their upcoming book, "Mordenkainen's Tome of Foes", WotC are going to introduce a "blessing of Corellon" whereby they can change sex at the start of each day.

Which is annoying, for two reasons. Firstly, the makers of D&D really need to get past their fetish for elf-love. Whether it's 2nd Ed's "Complete Book of Elves", or 3e or 4e's 'elf for every class', or this... it's just a pain that every time the designers think of something cool to add to the game, they promptly tack it on to the elf. It's frankly boring. (It's also limiting - if you want a gender-fluid character, you should play an elf?)

The other reason is that, naturally, the elves I'm using in my campaign are different - Corellon doesn't exist, the elven society has much more fixed gender-roles, and so on. So that bit of lore doesn't really fit.

That said, it's an interesting idea, that I'll promptly be stealing... just not for elves. So...

Eberron, of course, already has one gender-fluid race - Changelings have the ability to change sex (and much else) pretty much instantaneously. I'm inclined also to declare that Dragonborn and Dwarves are gender-fluid, to a greater or lesser extent. Specifically, I'm inclined to suggest that Dragonborn are capable of changing sex over a period of some weeks/months (and, as a corollary, that Dragons are also gender-fluid in the same way), while Dwarves adopt a sex at puberty, after which it becomes fixed. (I'd kind of like one more, changeable daily, but no candidate leaps to mind.)

Finally, I'm inclined to rename and reskin this trait as the Blessing of Li (goddess of passion), allowing those who have it, who may be of any race (yes, including elves), to switch sex each day - becoming male, or female, or somewhere in between (or even none of the above).

(And really finally, as I've noted in a previous thread, I'm of the view that Warforged and Shardminds have neither gender nor sex - it's not in their nature. This contrasts with a theoretical race with a construct body into which a human (or other) soul is transferred - which would probably be sexless but have a gender. Or kalashtar, where a human body is possessed by an alien spirit, and so where the two might not match. Basically, there's room for vast numbers of options, for people who want them. And for people who don't, they're easy enough to ignore.)

As for why: well, why not?