I agree with your take on this one and see a lot of validity in Don's comments as well. Based on what type of Aikido training is available to a Aikidoka, one can incorporate other forms in during some classes if appropriate or during open mat time. I have found that there are often others who feel the same way but have not spoken up for whatever reason.
Personally, I incorporated my karate background, and now am incorporating Kali and Krav Maga as well and it all seems to blend. Just the other night in the changing room I was speaking of incorporating other arts to compliment my Aikido and I found a guy who said "I'm in."
I'm not saying necessarily to mix other martial arts into your Aikido.
I think Aikido is adequate on its own. The principles are sound, the same principals that have been in use for and combat effective for centuries. I'm saying their might be, in some schools a lack of training in aliveness. No live uke. If you never have a live uke, how will you learn to defend against one? If you don't ever train to guard your face, what will you do when some one kicks it?
I think the core principles are adequate and universally adaptable to any attack. But if you have a static uke holding your wrist forever, you might never get there.
The kata is key, don';t get me wrong. You gotta walk before you run.