(BYU won the title in 1984 anyway, so even though they were snubbed, it didn't end up mattering)
BYU hasn't had a team that was really an NY6 type of team since 2001 (pre-Staley injury). They were good in 2006-2007, when they won the MWC title, but Boise State and Hawaii would've taken the G5 auto-bid from BYU those years anyway.
The only argument you can possibly make is that joining a conference could improve the on the field performance. Without that, bowl access just isn't worth anything because we have to be the top G5 team anyway.
My counter-arguments are that BYU's money, P5 games, and TV exposure would all drop like a rock (relative to independence) and with it recruiting would go down and the on-the-field performance would suffer.
If the on-the-field performance doesn't improve in a conference then all you're doing is trading regular season P5 games for absolutely nothing.