There are many reasons U.S. Presidents don't have unlimited power to classify, declassify or in some cases even KNOW classified material -
- They may compromise programs that predate their administration containing information vital to national security now, and long after their term ends
-They may unknowingly compromise human assets in the field, costing lives and destroying ongoing intelligence gathering
- They may, by publicly sharing or describing imagery or information about persons, places, things foreign or domestic divulge the methods & resources used by US Intelligence to gather that information, revealing crucial technical information, capabilities, assets, and partners - blinding and deafening crucial intelligence channels that may have cost hundreds of millions or billions of dollars and human lives
- The President - one fallible human being - cannot possibly see or consider, and lacks the full Technical, Historical, Sociological, Psychological, Economic, Military & Political ramifications of abruptly publicizing extremely sensitive material "in the moment"
*However*
As the Commander in Chief of the U.S. Military in its entirely, outranking all including 5-star generals in time of world conflict, one could argue The President DOES have the capacity to view and interpret all levels of classified material, and SHOULD be able to share select information with the public - HOWEVER, PRIOR TO DOING SO, should be forced to seek the counsel of their advisors, military advisors and intelligence analysts familiar with the source(s) of the classified material to consider any and all risks that publicizing the information would create.