A lot of those real world objects no longer exists, or are less frequently used than their counterparts, so I sort of see why moving away from that design language makes sense.
I'll hold of judgement of "Liquid Glass" until I've seen and used, but I don't feel like it's necessary. It's certainly not "the biggest" design update ever. System 9 to MacOSX was still greater.
This isn't really Apples fault, but I also expect others to start implementing something similar, but badly. Apple do have a point that this is something that only Apple can do well, because you do need to ensure that hardware can keep up. We're going to see other attempt something similar, but it won't been nearly as polished.
Overall I still feel that Apple is trying to force to much functionality into the phone platform. It would be really lovely to have an iOS light, that does less and with a simpler UI/UX.