It’s more than psychological. As i mentioned in my earlier post, movement around the aircraft or access to facilities is severely restricted when carts are in the aisle. One a wide body you generally have WCs at the front and rear, so you can usually get to a toilet - within your cabin!! - if you really have to.
On 737s/a320s there also nowhere to comfortably wait for the WC. You’re literally standing in the aisle and have to shuffle around to let the person out. And then you have to squeeze past everyone else waiting.
There’s no ‘breakout’ area to stretch your legs, grab a snack and have a couple minutes respite from your economy seat.
People may not pay too much attention to the aircraft type, but they ‘know’ once they’re on!