For example, certain versions of kokyu-ho seem incredibly unrealistic unless the guy continued to hold your hand throughout the movement. This is obviously ridiculous in a real life situation.
Answering this question was a big one for me. If you had some kind of weapon you were trying to use on "Uke", would it be ridiculous for him to continue holding.
I had a problem with not only Aikido attacks (like wrist grabbing) but also the commitment to the attack. I remember people saying to me "well wrestlers grab the wrist all the time. So wrist grabbing must make since." However in Aikido technique, there is a need for the attacker to continue holding the wrist. In unarmed martial arts, this is not a sound strategy. As soon as you apply something like a nikyo, your attacker will simply pull his hand away.
This changes dramatically when you add weapons to the situation. Now the attacker MUST hold on to your weapon hand, if he doesn't then you simply use your weapon on him.
You should try sparring with some wooden knives, or padded clubs, and see what turns up for you. It changed my whole practice, for the better!