Re: Regrading grabs in Aikido...
Because it was part of the curriculum. The problem with following a curriculum with no understanding the real context as to why certain techniques had to be there is the tendency for actual practical technique to become stylized.
Stylized technique become empty forms. Much of the repertoire in most traditional martial arts have stylized or idealized technique. It's in the curriculum so it's practiced without complete understanding of the purpose, over time the meaning is lost. I'm sure Osensei understood the purpose, I'm just not sure it was imparted.
Because a sword stabbing move is not like a boxer's punch. If you understood weapon based fighting you wouldn't have to ask this question.
Holding a long weapon with an end grip like a sword doesn't make for efficient stabs. However it makes for an efficient slash. Holding a long weapon from the middle or 3/4 grip like a staff makes for an efficient thrust, but not necessarily for efficient slashes.
Take the sword and hold it in one hand (right) and take a knife and hold it in the other (left) makes for an efficient slash and thrust movement with both weapons.
Boxers don't fight by holding their fist on top of each other as if they're holding a sword. Do you make a two grip yokomen strike? No. Do you make a two grip shomen uchi strike? No.
You need to understand the nature of the weapon.