Morihei's deep involvement in the esoteric Omoto-kyo of religion and his varied experience later seriously altered the art into something more philosophical minded.
Have you ever read an account of Jpn shamanism (and Deguchi fits into Eliade's definition of shamanism)?
It's not for the faint of heart. It's not loopy new-age puff for the glazed of eyes and the fixed of smiles. Those folks faced death when they went on their mountain retreats. Ascetic is different from esthetic. They climbed tough peaks for hours. They sat fetal for hours despite the pain in their knees and backs. They sat like that in tiny rooms with hot peppers burning in the center of the room burning their nasal passages and throats. They hung each other over huge precipices. I think Helen Hardacre has an account somewhere if you want to chase it down.
If anything, Ueshiba's infusion of spirituality probably made aikido--or aikibujutsu or whatever we're calling it today--tougher, not easier.