A lot of bad mouthing of shomen uchi. . .
I think that a lack of understanding of shomen uchi and yokomen uchi, both on the raise and cut, greatly contribute to the difficulty that so many aikidoists seem to encounter in fielding strikes of all kinds.
In fact, I think that one could safely call shomen uchi the most basic movement of the hands in aikido.
Yes i agree that many people do not understand the reasons for training against yokomen and shomen attacks. The reason for training againsts duch attacks are to train you not to "avoid" the attack as attackers will follow you the moment they see you move off the "centre line" prematurely.
I found that entering in (irimi) and moving your opponent off the centre line (after the attack) at the last moment is one of the best ways to deal with it, as opposed to trying to avoid (the exeception being shomen avoidance). also shomen striking is derived from the sword and put in place by Ueshiba for a reason.
This is hard to explain without actually seeing it for yourself, but hope this makes some sense .