regarding the QB sneaks, i have never seen a QB get hurt on a sneak. it is like a big mush pile, as opposed to bodies flying around at high velocity. the good sneakers like brady often seem to find an open gap and slide through there. from my perspective at least, i don't think the qb sneak is a big injury risk play.
regarding your last point, yes a 78 yard TD is better, but that is not what happens with any frequency, even for the dolphins with all of their weapons. this i think is where simple analytics can be misleading. using simple numbers, if throw on 3rd and 1, your average gain on a successful play might be 8 yards, but you might convert only 50% of the time, so the expected value is 4 yards. if run, your average gain on a successful play might be 1.5 yards, you convert 90% of the time, so your expected value is 1.35.
so 4 is better than 1.35, therefore always pass, right? absolutely not. what the expected value calculation ignores is the value of extending the drive, as opposed to having to punt. in the case of running, 90% of the time, you get 3 more downs. the value of that more than offsets the fewer expected yards gained by running vs passing. basically you just want to call the highest probability play that converts the third down.
further, if it is 3rd and 2, if run, even if dont make, you often turn it into 4th and 1, then much easier chance of converting the 4th and 1 than the 4th and 2 if pass, and you fail 50% of the time. this is the eagles tush push strategy. 3rd and 2 or 3, they just tush push, and do it twice if they need to, almost always get the first down. free money for those guys