Any chance that FAA would allow (the flying portion of) Flight Reviews to be completed with the CFI standing on the ground? Would this not be as good as or better than the CFI sitting in the backseat?

I'm not a CFI, but I don't see the magic in having the CFI in the backseat. What could not be accomplished with a preflight briefing of expectations, a radio, and maybe a pair of binoculars and/or *.igc flight log review? And/or a CFI-tuggie could fly the tow plane, observe the aerotow from that position and maybe even observe the glider pilot from the air.