Ordinarily, on a purely personal note, anyone can walk away from an experience and create a positive perspective for themselves in order to move on. It's called coping skills that we all develop as we mature into adulthood.
The difficulty that Former President Bush carried with his persona was the additional weight of the Presidency. He was beholden to the precepts of that office as sure as any prior president was and his accomplishments are weighed not just by the four years he served, but by the legacy he fought to rule over. (Note: every president serves only four years, regardless of successive terms. The electorate changes, thus, recasting the role of the president.)
Fair statements are made by many people, however, the final take is that once someone has served in higher office, or any public office for that matter, they are required to step down.
Politics heals itself by allowing the following successor to take helm and lead. Continuing to ask if someone has succeeded or not will only leave the task of the incumbent in greater danger, even if incrementally.
It should be said that in all likelihood, President Obama will only serve one term if stones, pebbles and sand are cast his way to grind him down.
The hypocrisy of any political philosophy that once held the great accomplishments of two-terms prior should reflect likewise upon the gravity of the incumbent.