I have posted this similar suggestion on steam. I put it here as it contains some extra suggestions (higjlighted with bold typeface):

I understand your opinion, and I know that a lot of OFP/Arma fun thinks the same, but maybe you have missed the first word of the title:
OPTIONAL.

I knew someone will bring this up.
First of all:
AAF and FIA IS talking in English with greek accent!
Second:
If player is not OPFOR they should talk in their native language.
But as soon as I'am with them, how realistic is that I cant understand the orders given to me? I have to learn Farsi to play as OPFOR?

/*They should have thought to it when they've recorded the Farsi voices, the same guy could have said the same in English too and it is done.*/

I know there are higher priorities, but it would be nice to have this option in the future...