And I'm on mobile now but I'm sure they were awarded for some things having to do with the Iraq War.
If presidents commit crimes, that's highly notable (and a big deal).
The Obama presidency wasn't completely scandal-free, but there wasn't much opportunity for Pulitzer level investigative reporting against him specifically.
https://en.wikipedia.org/wiki/2013_articles_about_the_Depart...
It's more about a press corps that let Obama get away with things they would have never given somebody like Trump a pass for.
For example, look at the press reaction to Obama refusing to prosecute CIA torture vs. Trump nominating one of the career officials Obama previously gave a pass to to head up the CIA.
Likewise, I doubt we would give Trump a pass for attempting to move due process free prisons like Gitmo onto American soil.
> When Obama took office, in 2009, he declared that he would not prosecute anyone involved in the C.I.A.’s interrogation programs, not even senior officers, among whom Haspel was one. At the time, Obama said he wanted to look forward and not back. But the past, as Obama well knows, never goes away. With the prospect of American torture looming again, I wonder if Obama regrets his decision. After all, people like Haspel, quite plausibly, could have gone to prison.
[0] https://www.newyorker.com/news/news-desk/the-new-c-i-a-deput...
Watergate investigation of President Nixon in 1973: https://www.pulitzer.org/winners/washington-post
If you expand the scope of "investigation against a president" to include the actions of his administration, then you'll find more examples:
1987 National Reporting Award for the Miami Herald's reporting on Iran-Contra (Bob Woodward of the WaPo was also a finalist on the same topic in this category) [2]
2011 Editorial Writing to the WSJ for its editorials challenging Obamacare [3]
2014 Public Service Award to The Guardian and the WaPo for the Snowden revelations [4]
[0] https://www.pulitzer.org/winners/photo-staff-0
[1] https://www.pulitzer.org/winners/maureen-dowd
[2] https://www.pulitzer.org/winners/staff-21