I would personally consider the 2018 Mac Mini to have a design flaw as the case design doesn't allow for good Bluetooth reception and using USB 3 so it would lose connection to my Magic keyboard and trackpad at least once a day which I personally found extremely frustrating. I've also had 2 iPad Pro smart keyboards fail within a year with the 2nd one only seeing light usage. It seems like whatever conductive tape Apple uses doesn't handle humidity well and corrodes quickly where I live. I'm concerned about my 2018 MBP's long term longevity keyboard aside just from the awful awful thermals that shoot the machine to T-junction in about a minute of actually pushing it but we will see. Probably the keyboard will wear out before that.
I think too many people confuse quality and metal construction. Yes, Apple builds nice aluminum enclosures but they neglect other details to achieve that.