I think the biggest issue for the upsets in the 1st round of the BET is simply having 16 teams, league depth, and parity. In the old days, and in many conferences today, the 8/9 seeds were simply not a good team. Today, the 8/9 seed is likely a 5 or 6 (or higher) seed in the NCAAs, and was in and out of the top 25 for much of the season. Combined with the #1 BE team not being as dominant, the 8 beating the 1 isn't the upset it sounds like on paper. It is easy to look at the double-bye, but personally I think that with or without it these are tough games.
in the regular season game with Georgetown in 2010, if I remember they were up something like 15-0, at home before SU went on a crazy run, so it isn't like they couldn't play, even though SU had a great year.
Up until 1994, (before the expansion started) no one was complaining that the 8/9 took place on Thursday night, and had played a game before playing the #1.