For 80% of the HS players HS ball is the highlight of their career. Parents always want "development" of their kids but a big part of hs players won't make it to college anyway so for them competing in hs games is a big deal.
And even the real prospects are going to remember their hs games more than some travel tournaments.
Travel is important but the travel season already is more than long enough, players can do both. People predict travel ball only for years now but every single guy who gets drafted still plays HS ball. I think they will continue to do both because hs is were your friends are and hs sports are a big social thing.