She was picked specifically because she was so weak. They knew the press would go nuts attacking her, there would be a huge backlash from the "base" because the attacks would essentially be attacks against the fundamental beliefs of the "base", and the result would be the massive rally of support that McCain enjoyed right after she was selected.
HenryKnoxFineBooks is right - now she's just a diversion from the fact that the neoconservative agenda has been rejected.
I think you're overreaching there a bit.
I agree that she was picked because she was "weak" -- but in a different sense.
It is well known that McCain
really wanted to have Joe Lieberman as his running mate... I think he was simply told "NO" by the RNC because they knew that THAT would result in a literal rebellion at the convention, the GOP was forced to swallow McCain, but even for the RNC flunky types there IS a limit... I mean running TWO Democrats on the GOP ticket is beyond the pale. {Plus it would have been the ticket of "TWO pasty old white men" -- not a good gamble versus a charismatic young Black Guy.}
McCain's OTHER possible choices (Romney, et al) all had their own "teams" and "factions" and would require him to compromise/share power... something McCain was absolutely ADAMANT that he did not want to do.
So I think they MAINLY chose Palin specifically because she did NOT really have a "team" in the normal political sense. She's a governer, but of a state with such a small population that politics are pretty "frontier-like" and rudimentary. She never really had to (or had the opportunity) to establish a coterie of politicos -- and so (it was thought) would not really present any power challenges to the McCain staff.
And so, Palin came with three "things" in her favor: 1) Most importantly she was a Woman... this to counter the Hillary "meme" and add a [purported] "minority" to counter Obama's ethnic appeal. 2) She was "young" offering a balance to McCain being "old" {and no they didn't think that through far enough}. 3) She was a State Governer (and therefore a "Washington Outsider"). 4) She was a virtual unknown to the press and they figured the media (and the "base") would simply gush over her "curb appeal" -- they were right about the GOP base, but wrong on the media.
But in the end I think it was mainly about POWER -- and the fact that Johnny McCain and his staff did NOT want to be upstaged by someone else's team on their ticket.