I find the controlled ditching hypothesis less psychologically puzzling, not more, for at least three reasons: ego, agency, and practicality.

First, successfully ditching an aircraft at sea is the ultimate test of piloting skills, and possibly one difficult to resist for the ego of a seasoned captain on his final flight.

Second, it seems out of character for a meticulous pilot to just let the aircraft slip out of his control and crash haphazardly at the very end of a carefully-plotted sequence of murderous steps.

Third, a ditching would better obfuscate the final resting place of the aircraft compared to an uncontrolled dive, as it would result in fewer scattered debris floating away.