If I were to speculate, and say it's probably because (1) they might not be interacting directly, and saying "(possibly indirectly) interacting" is a lot more syllables than "talking"; and (2) "talk"/"communicate" emphasizes the information-theoretic content, whereas "interact" is somewhat more likely to be interpreted in terms of interaction strength. (If two systems are "barely communicating", they are transferring a small number of bits, whereas if two systems are "barely interacting", the influence in displacement/impulse/temp/whatever is small.)

Shannon's original paper was "A Mathematical Theory of Communication," which actually studied radio communication, it's since been generalized, and there's no reason to rename jargon so outsiders can better understand it.

It was actually "The mathematical Theory of Communication," where communication was studied over any channel not just radio.

The paper(s) revolutionized several fields!