Paul, sorry, but you've lost me a bit here - are you saying aikido doesn't prepare you for combat or aikido with only the kata element present (no sparring etc.)?
The later. The body adapts to the demands placed upon it. If you want to be a great swimmer, you have to swim. If you want to be able to have "combative" skills or "self-defense" skills, a part of one's training has to mimic "combat" or "self-defense". I firmly believe this to be true, not just for aikido, but for all martial arts/martial systems/martial sports.
Is that more clear?