Just as a means of establishing rapport with foreign leaders (and some domestic ones), it would be advantageous to have the guitar playing ability of Hendrix (or any fine guitarplayer (Clapton, Harrison, Richards, Vaughn, etc) As a guitar player myself, many times I've played Hendrix' song Purple Haze (both in clubs and casually) and seen people's demeanor change from negative or disattached to very positive, friendly and tuned in.
As for all the rest of it, if Hendrix had gotten himself schooled on the ins and outs of the nation's tasks, by his advisors, he well have done a good job as president. One thing we know. He was capable of overcoming tough technical obstacles (like how to create/play interesting riffs on the guitar, and combine chords into pleasing progressions). That's not easy. He had the inner toughness to do that. A characteristic essential to being a good president.
PS - If anybody doesn't think good guitar playing is tough, visit any pawn shop and see how many guitars are hanging along the wall.