I'm not sure - I'm of the opinion that there are 2 schools of practise;
1. you use timing and disruption of balance to throw person (feet tend not to be fixed)
2. you use your hips and rooted feet to throw someone
When I've watched vids of Ueshiba he seems to throw i one of 2 types:
a. leading them arounf, then overextending them to throw them
b. turning them around their centre
Thus Ueshiba does not appear to force or push the attacker away from him - they are either lead, or they carry on in the same direction they were going (albeit, underside down).
Also, Ueshiba can be seen to be doing both 1 & 2 (more of 2 in his younger years). I think that timing and balance isnot always effective (1), also that (2) is more difficult against heavier/larger opponents.
In my mind we can use force - but only when the uke is unable to resist it i.e. we take balance, and then it is our choice whether to throw hard or soft. Upper body strength can be helpful in throwing people long distances or very hard - but even then, it is most effective when the whole body is utilised as well.