I totally agree with you on the iPhone X haha. That thing is like a wet bar of soap. 😂 the newer ones though, with the 11 Pro that I have for instance, have a different texture of glass on the back that makes it much less slippery. It’s more like a matte/frosted finish on the glass. Plus the squared edges of the 12 series makes it easier to hold on to as well!It could be that too, but I just don't get that about apple design philosophy, designing products that basically HAVE to be kept in cases to be useable.
I still use an iPhone X, and I think it is practically unseable without a case. Why? The thing is so damn slippery, it will easily slip out of any pocket or fall off any surface and I just find it very annoying whenever it's not in a case. Sure it looks beautiful, but I just wish they'd design their products more so they're great to use 'naked' if you want to use them that way.
I haven’t had a case on my 11 Pro for about a year now. I have a screen protector on it of course, but with the ceramic glass being 4x more resistant to drops on the 12 (and fingers crossed they bring it to the back as well on the 13 series…) maybe you don’t even need that anymore!