Having thought about this very thing while there yesterday, here's a photo I took of the back window installation.
It is so simple, sitting in a cuff at the bottom edge and being glued in place around the edges, I think it will lend itself easily to later upgrades that would let the glass retract, or, be removable.
Here's another view.
There appears to be adequate room for it in the space between the back wall and where the roll-down bed cover retracts to roll up at the base of the back wall to allow a future version to store the glass there. If not there, it could just as easily be mounted on the inside of that back wall and retract behind the seat.
There could be an aftermarket version of this made available which will retract/store the window to allow Camp Mode to heat/chill the sleeping compartment.
Those two black vent panels in the back wall could also be made to go through to the sleeper as a way to move conditioned air from cabin to bed. It does appear there may be a few different ways to solve this without much trouble.
It is certainly nothing for anyone other than an early adopter to get their knickers in a twist over.
Please accept my apologies for taking a positive and upbeat slant on your rant.