I don't second that. If the benefits form soldering everything together outrank the possible benefits of theoretical future upgrades, then I'd prefer the soldered version. Having the SSD straight on the mobo as well as the RAM you can in theory have a nice custom design that is slimmer allowing for other things that need to be bigger like the battery pack. Being able to fill every single cm^2 with battery that is not a standard rectangular shape would also increase the battery life substantially.
If the specs of the laptop are reasonable to be also fine in 3 years (like 16GB RAM + 256GB SSD are to be fair), then I don't see a problem as when you really need to upgrade you just purchase a new laptop and sell the old one. There are plenty of people who will take a well configured laptop off your hands and not send it to a landfill so the recyclability is a lesser issue and only comes at the very far end of the lifetime. And then it won't really matter if the SSD is in a 2.5" bracket or soldered onto the mobo as it'll still end up either recycled or in the landfill.
Yes, single component failures would reduce the lifetime of such devices, but hopefully in a tight and integrated system the failure rate is smaller (no bad contact issues etc that might cause voltage fluctuations and damage). Overall I'd not say that is a major concern. I'd rather take 12+ hour battery life in an integrated laptop over 6h in a swappable one...