Re: Aikido Techniques are Weapons Techniques
To echo what George has said above, it is my understanding that the assumptions of aikido include edged weapons and multiple attackers. I think those two features are very important in understanding why aikido is the way it is. Without assumptions like these, say the assumption was no weapons, ungloved hands, single person, then something like BJJ or sambo might be the form to follow that function.
But to disagree with a few other posters above -- aikido isn't straight jujutsu or grappling with weapons either, in my opinion. The other concept that helps me to understand aikido is that the jujutsu is more properly powered by sword mechanics. I find that while aikido waza can be powered like jujutsu and function it functions even better when powered like sword waza. This makes things doubly difficult because one has to then understand what sword movements are like and how they differ from other types of power.
Interestingly there is a similar issue in Wado ryu karate from what I understand. To do it properly one must do karate with jujutsu and sword mechanics. If one does it like Okinawan karate then it doesn't work the same.