i assume it was zerg rush example, but still

you talk too much about high risk - high reward.
where it is in aikido?

if you are shoveled you have 2 options - dm opponent shoulders or go for turnover with free hand. thats it. what are the risks for your opponent? none if he use the brain.

where is risk in using contracted wrists or low grabs?
none. at all. when you contract wrists you get huge advantage because you suddenly in one turn, get inner grab and disable opponent's wrists and get direct control over his elbows. one turn, one move that can not be countered if not anticipated and you are left with 2 active joints less.

of course you can win when you are caught with inside grab, but it's an uphill battle, since you are in disadvantage when your opponent raise arms and extend pecs, you can not save using wrists since you don't have control over it and when he extend wrists, your elbows can't counter it.

if you get low grabbed your options are limited aswell, you can try to counter incoming lift by double grabbing torso so he would not be able to fully raise arms, or you can go for dm, or again, you can go for turnover with free hand.

where is risk/reward? if you care to talk about cheese in aikido, care to explain me where is this risk, without all times favorite throwing burst and leaving claiming to be victorious.

i will probably waste a hour or so to make a graph showing what joints are required in order to play effectively in each mod when i wll get back home, just to make it obvious.