The recruiting benefit is secondary.
With more games in Hawaii and against UH, BYU could commence nearly every season with a Week 0 game. This could help BYU's scheduling. The extra week would allow for a warm up game before the daunting early-season schedules and improve the overall schedule.
For instance, the start to the 2019 schedule is brutal. What if we had Liberty or Idaho State in Week 0, because we play Hawaii later in the season? That would give us a nice warm up before the Utah-Tennessee-USC-Washington stretch. Or, host Hawaii in Provo over Week 0 (using Hawaii's scheduling flexibility) and delete the late-season Idaho State home game. May be even make the BYU-Hawaii game the Week 0 game every year, whether in Honolulu or Provo.
Look at the next few early-season schedules if you were to add Hawaii and Week 0.
The extra benefit is the increase in TV value, from both the additional game inventory and the scarcity of college football games available during Week 0 "opening" weekend. With frequent games in Honolulu and against Hawaii, BYU could become a Week 0 staple.
And, BYU v. Hawaii has rivalry embers and is the type of consistent game that could add predictability and enhance our independence schedules.