also, kotegaeshi has a certain set of pre-requisite move in order to take uke's balance. So, it's easier for us to twist their wrist.
and moreover, most of aikido techniques requires a flowing force from the opponent. If he's standing still, It will be hard.
And... you know... if the guy is standing still, then he's not coming at you to do bad things, which means he's no threat, so the aikido - taking uke's force to return the energy back into him or have him pass it into an object or the ground - just doesn't apply.
And, generally, the techniques which start with uke stationary, and which are called aikido, typically begin with nage/tori initiating movement... and that movement is what is taken advantage of, right?