Many of the history books on Samurai devlopment lean towards the change from "jitsu" to "do" as a turning point in the countries internal fighting. Lots of "do" arts began once the warriors found they needed something to do to pass time because they weren't fighting anymore (I am not referring to the removal of the samurai class, a la Last Samurai, but an earlier period). "Do" was a way to integrate the martial spirit into other activities, including self-improvement.
To me, Aikido is a codified fighting system. Because we no longer fight, "jitsu" is not [necessarily] needed, so "do" becomes appropriate. Even though some aikido people do not train for combat, the martial spirit of "jitsu" must be present to understand why and how techniques work.
Those that train in aikido but do not understand the fighting concepts behind the techniques are not learning aikido, they are learning how to mimic a movement. If you paint-by-numbers DaVinci's Mona Lisa, does that make you an artist? No. Why? Because you do not comprehend the elements necessary to painting a portrait.
Everyone has the right to practice aikido. People train for different reasons. But, when aikido people remove the martial spirit from their training because they feel that aikido is not a martial art, you lose purpose.
O'Sensei said alot of things about aikido. He spoke about love, harmony and peace and the purpose of aikido, but he never in all of his life said anything that would hint that aikido was not a solid martial art. I know that aikido is not only a valid fighting sytem, but a good fighting system that is capable of producing skilled fighters. I contend that a solid aikidoka can hold his/her own against almost any serious fighter. So why do many aikido people instantly concede that they are not capable of defending themselves against "serious martial artists" or "real fighting situations"?
It took Damien 4 paragraphs to concede this point. How long does it take you?