I don't think it's reasonable for "soldered" RAM on a tablet to be the first item on the cons. Is the lack of a replaceable CPU, math co-processor and cache memory a problem? Why not ask for a couple of PCIe 5.0 slots? x16 naturally.
People buying this want compact as possible performance using leading techniques. Something Apple has achieved to great success but x86 heritage is still not that great. It's the entire point of the design (efficiency through integration). It's very unlikely RAM will fail. Upgrading RAM is a separate issue, but going aftermarket is not really going to save anything these days.
Honestly NBC should really try to enter the mid 2020s. Repair-ability is an important modern consideration particularly for batteries, keyboards and ports (things that will definitely wear) and screens, but it's not so much "soldered" RAM, which implies the vendor arbitrarily soldered DIMMs to a board, but in reality it is fully integrated at a low level that does away with layers of connections and transmission distances.