IMHO, yes Aikido is still a martial art, therefore important and useful in a self-defense situation.
It takes longer because you not only have to learn a different way to move, but also a different way to think. The change and unity of body and mind is not a simple task.
To decrease time, go slower initially and learn the technical tactics and the strategic principles and concepts.
OK, I'll do that" "...To decrease time, go slower initially..."