George S. Ledyard
The requirement of relaxation, both mental and physical, needed to execute technique on this level is, for many people, quite transformative. Aiki requires a willingness to "connect". Most Aikido is done by people who do not really wish to connect.
The "fighters" wish to win, to defeat, to maintain their separateness by overcoming the "enemy", whoever that is. Generally, these folks have technique characterized by a lot of strength and tension.
The "spiritual" folks go to the other extreme and, despite their assertion that Aikido is about "conflict resolution", simply remove all conflict from the practice. Their practice is generally characterized by non-existent attacks, lots of graceful movement with little content, and, surprisingly, no real connection at all, just avoidance. In my opinion, both of these archetypal groups are fundamentally motivated by fear at the heart of things. Aikido practice is fundamentally about transforming our fearful natures into something else.
Flip sides of the same coin. On the one hand "fighters" attempt to eliminate, and "spiritual" types attempt to avoid, the sources by which they both fear their freedom will be diminished. Aiki, seen as a cyclic process allows one to act fully when the opponent cannot resist, and allows the opponent to act fully when one does not resist at all. Perfect freedom for both. No fear necessary.
In juuji, there is absolutely no resistance, it creates resonance feedback and a creative, chaotic development gives rise to sequences of interaction that neither could have predicted (takemusu aiki) -- which is not possible if either one avoids joining in the conflict that drives it, and impossible if one is competing to win or defeat the opponent in that conflict.