Sounds like we hit an area of interest of yours....just to elaborate a bit on your point about the 150, if I understand correctly the did 'fix' the offset problem, but they still sell the F-150 "Classic" without the sturdier structure as well. For those who don't want to be as safe as possible I guess.However, the 1996-2003 F-150s had a 5 star rating like the Sienna, but was an abyssmal disaster in the offset. Ford fortunately fixed the the vehicle....7 years later.
I think your points should be well taken, and you're absolutely right that an SUV is not inherently 'safer'. However, in average accidents (that being rear-end and T-bone) I'll take a 3 ton vehicle over a 1 ton vehicle any day (if that's your only issue)--you just can't mess with Newtonian physics. I do love that my Prius has the 6 air bags, I always worried about those windows and support beams.