Why isn't this a rule in football?

Agreed, it makes no sense. Or better yet, the defense should get to choose, either adding 10 yards or whatever it is, or half the distance.

If it's 1st and 10 at your own 1 or 2, because the consequences of a penalty aren't nearly what they are at any other spot on the field.

Not a bad idea.

Flip your logic and you get your answer.

How do you solve this problem on the other end when defenses have the advantage of only going half the distance? Can't move the chains.

Therefore, if the defense has to maintain this advantage on one side of the field, the rules allow the offense this advantage on the other side.

I think the main thing is there is no way to implement the same thing against the defense on the other side of the field.

An offense could be penalized 10 yds anywhere on the field while a defense could only be penalized a full 10 yds from the <-1 to the 11->.

One other scenario, say, if the offense has a 3rd or 4th & 10 on their own 3 yd line in a 2 min situation, a team with an excellent pass rush would probably like the 1.5 yd penalty.

It'd put a lot of pressure on the QB working in his endzone and the defensive line would have a better chance at a safety to end the game.

tl;dr-
It'd have some drawbacks but this is interesting
A lot moreso than removing 90% of the kickoffs...

They are attached by a chain that is exactly 10 yards in length.

Because you want the other team to move backwards, not just lengthen the first down yardage. Field position matters