Your post has caused me to pause and re-ponder my thinking about getting the XR. Like you, I like the idea of a metal exterior much better than one made of glass, no matter how good it is.
I'm not sure if Dow Chemical is still the company doing all the glass stuff for Apple, but the glass itself has reportedly been getting better and better with each iteration. But I read recently that the XR still had the same glass case as the original X, but had the improved screen glass that the XS and XS Max are sporting. And that has me scratching my head as to why??? I can't see the added expense of a superior glass on the back as significant enough to be a factor, particularly if durability is enhanced.
If you're like me, you're an absolute minimalist when it comes to iPhone cases. I tried the Otterbox and another one, but I hated the added bulk with a passion. And if you go for a Plus-size phone, you feel like you might as well be carrying an iPad. Some of these cases look as though you're getting ready to go into battle with an army of Terminators or something. I finally got a clear plastic case with a "drop factor" of 8 feet and had a glass screen protector glued to the front and have a phone I can still easily slip into a front pocket, plus better touch response than the plastic film Otters have. (Better fingerprint resistance, too.)
And as good as the camera is on the 7 models, getting what I consider to be marginal improvements offered by the XS or the Max isn't compelling enough for me to make the upgrade. And I'm not sure if the camera on the XR offers enough improvement to write home to Mom about.
I'm really hoping someone at Apple will put a bridle on Jonny Ives and reins him in. He's had free run of Apple since before Steve Jobs died, and he's gotten completely out of control since then. First his obsession was with how thin he could make everything. Now he's on a glass kick. Makes me wonder what his next "big thing" will be.