I think its becoming apparent that we are considering defence against different types of attacker, namely:
1. those who are very scrappy, with fast repeated and unpredictable punches, and who will tend to pull back into themselves whenever you grab an arm
2. those who do very powerful punches or kicks in a martial way
3. As (2) but can also counter strikes with counter punches or aiki/jujitsu techniques.
Type 2, is what we usually train to deal with, though they are more likely to struggle than we may expect. Type 3 may counter our techniques, especially if we also offer atemis. Type 1 is hard to do a technique on if they are very quick, but are also unlikely to do much damage.
I think the answer is strong and dynamic aikido technique where you can over-power your attacker without:
a. causing too much resistance ('forcefull' but not 'strong'?)
b. needing limbs etc to stay where they are (i.e. being able to move back into uke if they withdaw a limb)
I wonder whether it is worth practising technique with uke trying to withdraw their striking limb, to get used to blending with this movement?