This'll be somewhat of a lengthy lesson in history and fisticuffs. here goes..
Read in a book that a straight is where its at. It mentioned that years ago, when we were still using swords as main weapons of combat and war. There were many different sword designs used for war.
Some regions of the world developed round curve bladed swords designed primarily for slicing and cutting. These curved swords however had limited effect against the enemies armor. As they were meant for slicing and not penetrating. Thus making it only so effective in battle.
They mentioned that the Romans were on 'point' (no pun intended) with their Gladius short sword and shield. As this sword was made for cutting also but MAINLY stabbing and thrusting. It was also made shorter so its distance to the enemy in battle was less and it was quicker and more capable of thrusting through armor into the vital points because it had a 'straight' sharp point.
As opposed to the curved sword having to swing it sideways making it a slower path of travel to reach the enemy, and being only able to inflict lacerations but not being able to poke through armor.
Now lets take a look at how it correlates with boxing. You got your hook (circular strike) and you got your jab and straight right.
The way the hook is thrown only gives you so much penetration. As its thrown circular and on an arc. Those of you who box a little know a hook is relatively easy to negate and block with just a glove or arm up.
A straight or jab like the Roman Gladius however, offers much more power, thrust and penetration as well as being quicker on the draw. You can shoot the straight far into his abdomen, face, poke it through the openings in his guard. Where as the hook, you're limited to banging away on his guard just like the curved sword trying to slice through armor. You see the relation?
In theory our arms are like swords and we use them in almost the same way. To parry, to thrust, to swing. Just like we would in a sword fight.
Its amazing how sword combat and its theories influenced the science of Boxing so much huh? I found it fascinating myself.