Troubles with yokomen uchi

This morning in aikido, we took another step or two in our progressions toward "chaos" (or randori). Grouped in threes, each person took turns being attacked by the others with a basic shomen ate attack. The drill was to simple practice evasion with a slight touch (no technique). 

Not many problems there.

Then, we moved on to arced attacks, such as yokomen uchi (or a straight overhead "hammer" strike, or "upper cut" kind of strike). That's when things started to get a little messy.

The odd thing is, there's really not a lot (if anything) that you ought to do differently as tori from what you would do in any of the other kata that typically use a shomen ate attack. So why did things fall apart?

Well, I have one theory (so far). I suspect that, when people are attacked with something that's different from the norm (the same could be said of an uke with a weapon), their brains simply freeze. It's "unfamiliar" to the Conscious Mind, even though the Subconscious Mind could handle it just fine the same way it handles "normal" attack.

From what I understand, we in the Tomiki world tend to attack with shomen ate as uke so that, when we spend half a class as "uke" we can at least be doing something that's inherently, principally aikido (as opposed to a yokomen strike, which tori wouldn't apparently ever do). The Ueshiba world, from what I can tell, practice it routinely, as in this video:

Conversely, they hardly ever seem to use a shomen ate type of technique at all, as tori or uke.

As it happens, there are a handful of techniques performed from a yokomen attack in the higher katas. The problem there is, at least in our school, we hardly ever, if ever, get a chance to go over higher kata. So I'm left to wonder, would it be worthwhile to spend a class or two working on techniques just from a yokomen attack, even if the techniques are already fairly familiar (shiho nage, etc) just to acclimate the brain to an "abnormal" attack?

I think I might, just for the heck of it, schedule permitting, of course.