I think the point about the standard pins in aikido is
not that they're the most effective or quickest to do,
but that they continue the joint movement of the
technique. Thus the ikkyo, nikkyo, sankyo, yonko,
shihonage etc pins all work on the shoulder in the
same direction as the original rotations. We pin
that way to understand more about the technique,
not only to control uke.
Aikido isn't Judo. The aims of the pin and what we
mean by 'control over uke' are quite different. An aikido
pin allows us to control uke without pain while protecting
ourselves, and at the same time gives us the opportunity
to respond quickly to a second attacker by both disabling
the uke on the ground (for example by breaking the arm)
and being free to deal with the new attack.
Judo holds, OTOH, *usually* involve no strong pain, but
can't disable uke quickly if tori needs to deal with something
else (Emphasis on usually to stifle objections).