IMHO, it's the political game.
Bush is responsible for running the economy to hell over the last 8 years.
Now he tries to sort of handle the mess and leave on as good note as he can.
It just so happens that the economic crisis demands intervention according to most economics (not according to Ron Paul though, he thinks the politicians just should step back and let it all fall and it will be all good in year or so, never mind all the people who will have lost their homes, jobs and futures).
But since intervening means using tax dollars, he's in a jam.
Because the Republicans are on a losing streak, so the few of them who's left are not going to back Bush.
Because if they do, they too risk losing the mid-terms.
And the Democrats will not accept shelling out money without getting their voters jobs covered.
Hence the extra bills that the Democrats gets attached to the rescue plans.