I must say, even as a Packers fan, that Jackson is showing alot of potential.
The problem is though, like you said, the coaching staff. Another problem though is his decision making.
He seems to be a poor man's Micheal Vick or Cunningham at this point in his career. He lacks the athletacism Vick had/has and, apart from this last game, showed to have the same, if not worse, decision making, throwing the pass into all kinds of coverage.
Favre wouldn't have fixed your problem, but he would've been a short-term solution. I mean, seriously, Gus Frerotte? I know Favre's cap hit would be pretty hefty and he has a big contract, especially for one of the 'poorest' teams in the league, but if they could manage to sign him, wouldn't you want to have him starting? Jackson has been the second stringer for nearly the entire season, leaving it to Frerotte.
If I had to choose between Frerotte and Favre.. I'm pretty confident about who should start for my team.
Ofcourse you couldn't have seen the benching coming either, but having Jackson sitting behind Favre for a year or two wouldn't be that bad either.... especially if that got you a SB.