Nein!
Let me make two points...
First, the era is far less important than the sound. Strictly programming on era would put "Good Times, Bad Times" by Led Zeppelin next to "You Light Up My Life" by Debbie Boone. Two memorable songs, but highly unlikely to appeal to the same audience. Adding songs because they come from a particular era is as silly as eliminating songs because they don't come from an era. To my ears, WHTT has been adding songs because they fit their "sound" musically, no matter what the era. That's why you hear Michael McDonald from his Motown tribute - recorded in this millennium - as well as Motown originals from the 60s and 70s.
Secondly, I'd much rather listen to WHTT, which has a bunch of good and entertaining jocks on most of the time, than Jack or WJYE. Jack has nobody, and WJYE has nobody interesting. According to my sources, WHTT has done very well in attracting a younger audience, and has been beating WJYE 25-54 and 35-64. WJYE still wins in women demos, but not by the huge margins of the past.
Is the music important. Definitely. Is the value added by good and entertaining jocks a difference-maker? I believe so. In fact, I think that future of local radio depends on stations differentiating their presentation from iPod fodder, sattelite, and syndicated content. The "magic" of radio has always been in the one-to-one relationship between the jock and the listener. Jocks who understand that and know how to entertain beat the competition every time.