Quite often. Though nage isn't always holding a weapon, we teach people -- from day one -- that uke is grabbing for a reason, not just to hold nage's wrist.
The distinction between uke and nage is entirely artificial. It's useful for training purposes, but the assigned role shouldn't make much difference in a person's attitude
O.K. Fine by me. I shall now refer you to the following: To give distinction between uke and nage.
Have uke representing something that's not Aikido. (principle wise) Then see from that view a massive distinction.
For example, trying to stab someone is hardly in accordance with the philosophy of Aikido. However Aikido philosophy states it can handle such with harmonious motion etc.
Therefore it's good to look at it this way I say from the view of nage representing Aikido while uke is representing a determined yet non-harmonious other.