Thank you all for explaining the reasons behind the techniques that I need answers for
I see more involvement in the techniques and the "slowness" of the Uke's techniques is namely for safety as with the correct breakfall techniques when Nage throws Uke
Actually, not really. In Aikido, as it is in jujitsu, uke plays the more important role, which is to help nage learn. Uke provides nage with myriad learning opportunities, commensurate with nage's abilities and skill level.
If as uke, you change the premise of the technique, by changing the attack, or by resisting nage (over and above their level of ability), you deprive nage of a learning opportunity. That opportunity is wasted, and so is the time spent on the mat. Uke learns just as much, if not more, by simply doing their job - taking ukemi. Turn it the other way round... would you appreciate it if uke resisted and changed the attack, and deprived you of the opportunity to learn a new technique?
If, say, it was your first time learning how to put on a choke, and your uke resisted and fought back, or shifted so you couldn't apply it, wouldn't it be a waste of time? More often than not, it becomes a contest of strength, and neither of you learn anything in that encounter - except the truism that the stronger person will always win.
The slowness and highly cooperative nature of training is designed to inculcate correct body mechanics, with little or no effort. All too often, I see people muscling their way thru technique, in an attempt to complete the technique and put uke into the mat. That, to me, defeats the entire purpose of learning correct body mechanics - and how to use the other person's strength and force against themselves.
Which to me, is the entire premise of martial arts and self-defence. It's not designed for people who are already strong. It's to give the weaker person a tactical advantage over another's strength.
Aikido is not a force-on-force paradigm. It's about redirecting force, and outputing just enough force, on very subtle levels of sensitivity. That's why it's done slowly and deliberately. Training safety, is and should be a primary concern in any case, irrespective of what MA you're doing.