IDK if it's "70s" thinking, or just an outdated philosophy in general.
Many teams were still playing that game right up to the turn of the century.
I believe field position is still an important aspect, particularly if you are a conservative coach with a strong defense.
Having said that, the days of ball control through the "3 yds in a cloud of dust" are over.
More to the point, I would rather have an excellent punter, and average returner, than vice versa.
You can spin it any way you want, but 12 yds/gm difference on 4 punt returns is not a significant difference in field position.
Also, saying the returner alone is responsible for those yards, is completely dismissing the other ST players, and coach.