I recently read in this post/thread
that in Iwama aikiken they don't treat the sword as a cutting instrument. Perhaps this is just one practitioner's opinion and it's not the general, more authoritative opinion -- I don't know since I'm not an expert in that style. From an "outside" perspective though, I can agree with it seeing how they use the weapon, and how having a "kissaki" (mimicking the real sword) is not that critical. I also read somewhere that the kissaki was removed after a training accident involving somebody's eye...
It is true that in the Iwama weapons system the bokken is generally considered to be a striking weapon. Do you have a reason to believe that at some point, the founder held a different view (say, that the bokken is just an approximation if a shinken) and the change of shape reflects a change in the attitude?