I was surprised to learn elephants are relatively unpopular species. Elephants are popular animals irl (I thought, anyway!), and the elephants in AC are just too cute... Their teeny trunks and little floppy ears remind me of baby elephants.

I think they're a great inclusion, because they're super intelligent and empathetic animals IRL, and their AC design helps them fit in and feel cosy. Plus, there's such a great diversity of elephant designs, and I think they have way more they can do. I particularly love Chai (IMO the best Sanrio villager - yes, even over Étoile), Tia, Big Top, Dizzy, Ellie, Margie, Eloise, and Opal, and.. welp, I just named like half of them.
I don't understand at all why elephants aren't popular. Every time I've seen one in game, I've really adored them; it's never lined up that I've had one, but I did hang out with them a lot in Pocket Camp. So, I have no idea how to fix their unpopularity. There are a lot of underrated species in general (like frogs, although frogs don't have as good designs). I know this won't apply to all people, but there are a lot of people who haven't liked chubby or unusual body type villager species throughout the series, so I do feel like elephants are a victim of that, plus I guess the best ways to increase their popularity is a) make more of them, with more cool and cute designs to broaden appeal (Tia is quite well-liked in my experience! I think there are enough basic elephants that we can get really creative, like with Tia) b) make ones with slightly different models (like the kangaroos and so on - hell, there's an elephant with tusks), e.g. bigger ears? Don't know.
I personally disagree with the contention the best villagers are themed. I mean, some of them are - and Merengue is way more popular than the other rhinos, for example - but plenty of my favourite villagers just have solid designs, and I see tons of very basic villagers (especially Normals and popular species like wolves and cats) being popular. It's enough to be particularly cool or cute, imo, and have a fanbase for your species. But there's so, so much they CAN do with the elephant model if they're willing to get abstract, because they're basically just groups of circles with a protruberance. If you look at Pokémon and Pokémon fan designs, you'll see what I mean! There's also popular elephant associations they haven't explored fully, like the circus is a basic example, but there are MANY MANY MANY famous artworks, stories, and figures of speech associated with elephants.
Cyd definitely didn't get enough attention when the game out. He kind of reminds me of a puppy though!