The main reason i've heard Disney wants to do a VQ for MMRR is bc, as we all know, the Chinese theater can't hold more than 45 minutes worth of queue (they haven't expanded the queue, it's mostly the same). They're probably gonna have to snake the queue all throughout the entry area of the theater and potentially down to Pixar Place. Combine that with the ride system being the same as Rise and a lot of moving parts and it could have a lot of breakdowns.
Maybe they won't use the system, but if they don't i'm thinking they're feeling really good in the ride's reliability as a lot of WDW insiders are saying the plan is for the ride to launch with VQ.