The fact LG gave us a choice of different materials for the rear cover and REMOVABLE BATTERY already beats METAL DESIGN in the longer term.
I was reading different forums for BlackBerry Passport and Oppo about the pros and cons of sealed batteries vs swappable. Both BlackBerry and Oppo were offering REMOVABLE BATTERY as recently as last year. Of the dozen or so smartphones I've owned, only iPhones, the M7, and the Mi 3 didn't offer a removable battery. And while people can argue so what or we change our phones frequently to even care, I kinda am on the swappable side. It gives me a peace of mind with maintenance for the longer term. After a year or so, that battery degrades faster than you think.
Swappable battery benefits the user and gives them the choice on whether to upgrade or stick to a proven, reliable phone without worrying of sending it away and getting charged for the new battery and SERVICE fees. Sealed battery only benefits the manufacturer. This scenario applies with my now 10-year old Sony PSP vs a PS Vita I am borrowing from my cousin. My PSP lasted 8 years on its original battery until it went completely dead. I haven't bothered to buy a new batt (even Class A) for $10. But I know I can revive it again if I want to. If I owned a Vita, I have to go to a Sony service center to have it replaced for maybe 7-8x the cost and could be gone for weeks.
Removable battery for me with smartphones. I will buy extra batteries, store it somewhere for a few years, and be good to go when the original batt is completely dead. Expandable storage is also nice to have. LG still provides that along with Nokia on the lower-end. The Nokia Lumia 640 has about the right specs on what I need from a smartphone ("5/720p/2500 mAh) except being WP. I may never go back to any phone that lacks both those two features. It will start to look shortsighted when the time comes of needing a swappable batt or micro-sd card. Forget obsolescence, I want longevity.