"Ideally, of course, you should have matching tires on all four corners, and rotate them to keep them matching, "
Which is my problem with "better tires on the rear." With a FWD car, if the "better" tires (the ones with more tread) are on the rear, the "worse" tires on front will be losing tread at faster rate than the rears, leading to ever-more-disparate tread depths.
The only way to "keep 'em matching" is to put the (slightly) worse tires on back, until the (slightly) better tires "catch up" to the rears, due to a faster wear rate. Strictly speaking, you cannot rotate tires AND have the better tires always in the rear (on an FWD car).
"They also figured out that understeer (steer tires plowing) is much less dangerous and much easier to control than oversteer (back end sliding)."
And I don't understand why everybody nowadays thinks correcting for oversteer requires the driving skills of an F1 driver. Sure, it's counter-intuitive the first few times, but if you practice the procedure on snowy/dirt roads, it becomes second nature quickly. (Not only that, "practicing" this maneuver is FUN.)
Besides, the typical "people hauler" has such an understeer bias that overcoming that tendency is beyond "mismatched tires' poor power to add or detract."