This is a great post. I think many comments in the post cut to the quick... I am a big supporter of martial effectiveness as evidenced by physical skill, and I am a firm believer in maintaining the integrity of aikido through martial viability.
1. I believe aikido does not fall within the context of "martial arts" as the term originally was utilized; I believe many arts no longer carry the militaristic connotation implied from the "martial" pretext. This is largely due to the change in modern English to categorically classify a fighting system as "martial," regardless of its actual ancestry. At some point in time, chess would have been considered a martial art in which commanders learned how to deploy their fighting resources on a field of battle...
2. Aikido students desparately cling to its fighting roots with one hand while excusing their lack of functionality for higher purpose with the other. I take greater issue with this single dichotomy than any other argument for (or against) aikido as a fighting art. If it doesn't work, don't call it a fighting system; the problem is we have all seen aikidoka who are extremely good fighters and we can't explain why they succeeded where we failed. To this point I think I have heard many posts questioning why in the years since the death of O'Sensei has not one aikido student excelled to the skill of O'Sensei...
The Founder quite consciously did not have a ground fighting component in his art. It wasn't that he forgot... it was purposeful. The techniques of Aikido got larger than their Daito Ryu antecedents. This also wasn't just some random occurrence, the move away from martially applicable small technique to a larger type of execution focusing on internalizing certain principles both in the body and in the mind was done, I think, specifically to take the practitioner away from the fighting mind. Aikido was meant to be less practical for fighting.
I think this statement is very accurate. From my education in aikido, it appears that O'Sensei did temper his instruction to purposefully omit technique or restructure how he wanted students to emulate technique. I believe on a large scale O'Sensei, through his living students, was able to expand physical technique into a greater training. I believe the cost of that accomplishment was a less effective formal fighting style.
However, I also think he left intact those pieces he omitted or altered for a discerning student to find and incorporate into his personal aikido. I read consistently about aikido instructors (and students) who draw upon other fighting styles to re-energize their aikido. I know instructors use practice weapons to extract simple principles of fighting to evaluate proper stance, distance, or timing. I believe it is the challenge of aikido students to sleuth these answers as we train and discover how they fit into our aikido to make us a better student. I believe the most effective aikido is the patchwork of incorporating other traditional fighting styles to fill the gaps in formal aikido training. To some extent, it is a brilliant way to protect aikido - only the discerning students will persevere to the advanced levels of aikido...
With all that... A man climbs a staircase to a monastary atop a high mountain. He sees a monk sweeping the stairs as he approaches the entrance. "These stairs are immaculate. Do you sweep these steps every day?" the man asks the monk. The monk nods yes. The man continues, "It must take you a long time to sweep all of the steps; can you sweep them in one day?" The monk again nods yes. "You must sweep very quickly," the man concedes to the monk. Looking incredulous, the monk says to the man, "I've been sweeping this staircase for 20 years, I better be pretty %#$&ing good at it."