It appears to me that the mental fortitude and spiritual insite gained from aikido training comes as a result and side effect of training towards the goal of being proficient in budo. As has been said a million times, "Aikido is first and foremost budo". If someone wants to treat aikido techniques like a moving meditation to seek enlightenment or what have you, that is fine, but I'll never be convinced that it is aikido.
If a person takes up kyudo, their goal is to become the most accurate archer that they can possibly be. The tenacity and intensity of training that it takes to reach this goal is what forces the practitioner to grow and examine themself.
Sure there are easier ways to defend yourself in modern society. Buy a gun, a rabid pitbull, whatever...
But...there are also easier ways to hear music than to learn to play it yourself.