WHY Are All Nonhuman Aliens Naked?

This has been bothering me for a solid minute. Especially after I read Project Hail Mary and then watched the movie based on the book. I know damn well that Rocky was written with clothing on and yet...

Not a stitch on him. This is the latest in a long line of non-human naked aliens and I really would like a Doylist and a Watsonian explanation for this kind of choice.

Don't fight with me. It is a choice. The movie industry has been able to put clothes on fanciful creatures that, off screen, are actually puppets or CGI creations. I could argue that the offense is even worse when it's a CGI creation, because they could easily model clothes for that. They have the technology.

The people who made the movie out of Project Hail Mary had made tools and a tool belt for Rocky to wear when he was making stuff. Why not the clothes?

This isn't a new phenomenon either. Whenever an alien is represented by a puppet or animation, there's no clothes. When it's a human with bits on, then you get clothes.

Trust me, it goes ALL the way back. It's not to show they're animals. Many of these aliens are more advanced than Humanity. Like Thor from Stargate:

Doylistically, just the puppet is easier to make. Figuring out what Alien Fashion may look like is a bit of a task. Like, yay there's a body. What do we put on it that doesn't look like Earth++? Budgets, timetables and so on means that just having the puppet is often "good enough" for those making the thing.

Then there's shapeshifters. Yes, I could have picked on Odo, but he's played by a human actor with a wardrobe and so on. Human with bits on. Jake the Dog is an alien who thinks he's a talking dog through most of the cartoon series. In one episode, it's stated that he's wearing an invisible, skin-tight onesie. He's effectively naked and it's never mentioned again.

Yes, I know it's a cartoon for children. I'm using it to point out the ubiquity of that particular trope. It's in everything with a non-human alien in it.

And it vexes me.