It makes sense that the first ones to use this new standard would be Dell and Lenovo. They both have "business" lines of computers, which usually offer on-site repairs (they send the parts and a technician to your office) for a somewhat long time (often 3 or 5 years). To them, it's a cost advantage to make these computers easier to repair. Having the memory (which is a part which not rarely fails) in a separate module means they don't have to replace and refurbish the whole logic board, and having it easy to remove and replace means less time used by the on-site technician (replacing the main logic board or the chassis often means dismantling nearly everything until it can be removed).
