I agree with both schools of thought.
Some stations need personality; others don't. For some stations, it helps; for others, it doesn't. For yet others, it actually hurts. BEN-FM had managed to carve out a personality without jocks during the day. The station's snarky attitude and "J. Peterman" drop-ins have actually lent the station a fine personality. They've gotten this far and now jocks just seem unnecessary--and like an interruption. Will it hurt? Probably not. But will it help? Of course not.
"Active" formats like CHR, Urban, Rock... These stations absolutely need jocks (and preferably live ones). Background formats like AC, Classic Hits, Variety Hits seem to be able to carve out a fine little audience and "station personality" with the jukebox approach. Kinda sucks but what are ya gonna do?