I think part of the problem is that Obama has not campaigned - has not even mentioned - what his intentions are regarding Bush. At least not in any dramatic public way. So, it doesn't smell like Justice (even if that's what it is) as much as "O wait LOL".
But fuck that shit. Here's what's important: If by the laws of the land President Bush is or was guilty of one or more high crimes then you have serious problem. One way bigger than a mere corrupt and evil president.
See, as has been pointed out, this isn't an administration vs. administration thing. This is an independant judicial thing.
The consitution does not state that the check on the president's power is the next president. No, according to the American system of checks and balances, the Justice system should investigate and accusations of wrongdoing on the part of any citizen - including the president. If a sitting president is found guilty (or is hanging by a rope of his of his own making, a la Nixon), it falls to congress to initiate a congressional investigation and initiate impeachment procedings if necessary.
Again, it is NOT the incoming president's responsibility.
The problem with an Obama investigation is that any push to indict Bush or his cronies will basically point out that the American system of checks and balances suffered nearly a complete collapse during the Bush administration. Whether they were actually complicit or merely appallingly spineless is irrelevant: The Democrats were in it up to their fucking EYEBALLS and the Judiciary either turned a blind eye or can now be successfully stonewalled, either of which are huge problems all on their own.
The shitpile is compounded by the fact that Bush's crimes are not nearly so clear-cut as Nixon's. With Watergate there was a clear crime (break and enter, illegal surveillance, etc.) and a trail that basically led back to a President ordering some shady doings. In Bush's case it's much more of a case of immoral and dangerous policies enacted by the government. yes, Bush's crimes are actually much worse, but their guise of legitimacy is so much greater. This is aided by the fact that nearly everything was basically done above board, making it infinitely easier to rationalize them away. And if anything was done under cover of shadow... well, if there's one thing I would trust a Bush scion to do, it's cover his fucking tracks so as to avoid winding up like Dick.
Unlike watergate where the crime was blatant basic thuggery, recognised by almost anybody as a 'criminal act' Bush's crimes are things that people will debate as 'legitimate'. Hell, that's what your country was DOING for the past five or six years. Whereas Nixon was quickly abandoned by almost everyone, if the call goes out to prosecute Bush, much of the country will not be on board that train. And if you don't believe that, well, just go back and look at footage from any McCain/Palin rallies in September or October.
Now, if knowing this, you think the United States is in need of the long melodrama that will result in such an investigation, then by all means you should do it. The fact that the American democracy near bottomed out is pretty fucking important. But as with anything, there's a tradeoff. Such a debate will dominate everything and may even taint Obama. Certainly if the Democrats try to burn the GOP, well, the Republicans will certainly make sure the Democrats look like shit if no one else will. The Democrats can't take the high ground here because they fucking gave it away at least two years ago. They have been a key party to this travesty during most of the Bush administration. Or at the very, very least the last two years. Any true and honest investigation MUST confront this incredibly ugly fact, otherwise it IS just partisan revenge.
The alternative is to let Obama play messiah, talk about other pressing things (economy etc.), and gloss over the whole thing.
Both options suck a hell of a lot of ass. So the question is basically which particular cock would you like shoved in your anus today?