If you get the country through a major crisis, people will say you are great. If you see the country through two of its biggest crises people will say you are great. Maybe somebody else could have done better, but somebody else could have done a lot worse and left the country in even worse shape.
It's not really about ideology or morality. We used to say Polk was at least near great because he got the country California and the Southwest. Now we object to him on moral grounds. We are "right," but we did get California (for at least a while) and that can't be denied.
If you get the country through a major crisis, people will say you are great.
Not working out so well for Barry.
FDR, btw, did not get the nation through two crises. Like Barry, he nursed the nation along through an economic crisis he inherited, but rather than resolving, merely extended and, at best, diluted, and, at worst, deepened with a long line of unintended negative consequences. So, yes, it could have been far worse -- or a helluva lot better.
Cases in point: McKinley, Harding and Reagan fixed and did not screw up economic crises they inherited.