What really annoys me is that the under-bed spare (or any "trunk in bed" type feature) makes having a proper drop in liner impossible. A drop in liner increase

What really annoys me is that the under-bed spare (or any "trunk in bed" type feature) makes having a proper drop in liner impossible. A drop in liner increases the durability of a pickup bed by an order of magnitude and is all but required for certain use cases if you don't want to tear up the bed in short order.