Failing a rational explanation for the unprecedented use of presidential coercion, we must look at other irrational alternatives. To be fair, Bush got the ball rolling by demanding plans for Chrysler and GM but Obama has crossed into previously untried policy areas, over-riding the legal rights of the shareholders in the process.
If a company asks me for money to keep them afloat, I am a shareholder, period.
The American people are a huge shareholder in GM and Chrysler now, whether or not everyone wants to understand that fact. If we held a public election on Wagoner's fate, I seriously doubt he'd still have that job. The man who replaced him, as an internal appointment, is a GM career executive, not an administration monkey, so saying anything was done for the presidency's advantage is fundamentally biased and full of hot air. As you said yourself, irrational.
Lack of rational action for the past 50 years is what got us in this mess in the first place.
People were pissed off that the last administration allowed a bank bailout without good oversight and conditions. Now people want to be pissed over too much oversight and conditions. Fact is, there will never be unanimous content with anything done, because people will always have something to criticize. Criticism with suggestions for improvement substantiated by evidence and precedence is good, criticism for the sake of criticizing is worthless.