a sensei I know gets quite irrate when people talk about 'soft' and 'hard' aikido. I think a good grounding in basic, static movement is useful - and I think this is the type of movement some people refer to as hard.
However I believe aikido goes beyond that (and this is why it is different from ju-jitsu), to blending. To blend, we have to realise WHY we blend - basically because someone can resist non-blending if they get the feedback from the technique.
Thus we have a strong, commited technique, however; if we feel ukes body changing or moving in a particular way we are fluid enough to respond to that change.
Also, I think you can throw someone hard whilst blending, and also throw someone softly without blending. It is about directing force at the weakest point of uke. For example, when ukes spine is bent (and balance broken), the choice is yours on how hard you throw them because they do not have the posture to offer any resistance.
Thus probably we should be arguing about 'blending' and 'not-blending' rather than hard and soft.
Not blending is a process of learning technque, which all beginners will go through to some extent. To some degree whilst learning technique, but more ONCE we are familiar with technique, that is when we can learn to blend properly.