No worries. Sometimes "tone" is lost in text.
In terms of all the big names giving that direction to spread fingers, and all the video showing them doing it, I don't dispute it. But what I have yet to hear is WHY (emphasis, not yelling) they do/say it. I know it is not very "Japanese" to ask "why" when given direction, but I'm not Japanese..... What I am is a scientist/engineer looking for a solid mechanical explanation. The only one I have heard given (not on this thread) is that it increases the diameter of your wrist and somehow this creates a better/more advantageous connection with uke when grabbed. I've experimented with this and it doesn't hold water for me. Perhaps someone can elaborate...
Well, to be honest, I don't think most of them really knew why. It was what their teacher said to do, it worked for him, they did it and their aikido worked for them. To be fair to me, my first post addressed what I feel it does and by feel, I mean what I really feel when I do it. It helps connect the hands to rest of the arms. It's something that anyone can replicate. Extend your arms in front of you like you're catching a ball, not a forcible stretch, but just just extended. Do that with your hands limp and then do it with your hands open. Your arms feel more connected and full. a single unit rather than a collection of loosely jointed parts, neither tense nor noodly. IMO it's a simple, early teaching device to impart that feeling and if done during practice, some basic conditioning. Over time the connection should improve and become more complete over the entire body and you learn other ways to activate that connection. Ueshiba clearly made this transition at some point.