The most obvious shomen like strike is a beer bottle to the head in a barfight or something.
To say noone would choose a certain attack for reason a, b, or c assumes a certain orientation or experience of the attacker. To say 'this is not the best attack' for reason a, b, or c, might absolutely be valid, but it in no way indicates that the attack won't be used. $.02 from my perspective - which is worth about the same.
Well, why else would we train with it then
Obviously attacks will come down the centreline. The shomen uchi is just a generalized simulated strike down that line, so that we can train to react against it. The sword cut, beer bottle bat, heavy metal bat, 2x4 plywood, iron pipe, hammerfist, etc. can all come down the centreline. So attacks do go through the same motion. If it didn't, we wouldn't even bother to have it in the course syllabus.
The key point I'm trying to make that it's not really an Aikido attack
. "Aikido doesn't have any attacks!"... pure bull. It came from Daito-ryu, of course it has attacks. We just don't use them often. But when we do use attacks, I'm pretty certain all of you good folks of yudansha level must have better strikes than shomen uchi.
If not... well, time to ask sensei for atemi lessons