I blame the Love Hina for the entirty of the Loser Harem Male Lead. Before Love Hina, the harem male leads do have some redeming features besides just being nice guys.
Tenchi Masaki - l likeable regular guy who can destroy the universe and as of GXP at least seems to have his harem under control.
Makoto (EL Hazard, tv/oav) - Both versions Makoto is protryal as a likeable guy, straight A studen (mad scientist in TV) and got enough athletic ability to win a school race.
Gene Starwind (Outlaw Star) - Kinda like a ver of Ryo Sabea in space. Not a brain surgeon but good at tactics, good backup in a fight. Likeable and defintely not a loser.
Then Love Hina came
you guys see the result of that with every harem show. losers whose only redeeming value is being nice guy.