There are a lot of wimps, no doubt..........However, your notion that the Super Bowl teams didn't sell out late games is wrong. I just looked it up.
The only two games those four years that don't look like sellouts are this one:
December 12, 1992 Denver Broncos Rich Stadium W 27–17 10–4
71,740
And, the 12/26/93 game against the Jets that was one of the coldest games in history. 2nd coldest here and at the time, THE coldest. It was unreal............And, they still got 70K there. I'd be willing to bet it was sold out if that many showed up on that Arctic day.