Check out this video of a yoshinkan practitioner.
He starts with fingers spread wide while addressing uke. As soon as the waza starts, I only saw his fingers spread once, at the end of an iriminage/tenchinage, actually twice the other in a swariwaza grab. I have no idea whether this is intentional on his part or not, but he is clearly only taking the spread finger direction of Shioda Sensei in a static setup pose, not during execution of technique. (I don't think you can say Joe Thambu Shihan's aikido is weak or ineffective IMO). So once again why?
As discussed elsewhere on the site the last few days, Shioda sensei also said that their kamae was not to be considered a fighting stance, but was used to instill the center line. I take that to mean their kamae is used to impart a certain physical quality to the body that he feels is not only important, but one that will not be found otherwise. I recall reading that his kamae was not stressed this way in the early days of the Yoshinkan and they made that change because it clearly found something lacking in his students.
Go watch some videos of how they do things and give it a try yoruself, see if you feel anything. Obviously one cannot practice with the hands like that at all times, but IMO, the point is that with the proper kind of practice, you eventually don't need to do that to maintain that same quality in your body. FWIW.