I can speak as a Cybertronian. Our war mainly took place on uninhabited planets, but many of those that were inhabited were frequent targets of Decepticons. [He's trying very hard not to look at Megatron.] To mitigate immediate and future damage to the - usually organic - species, we remained in our alt-modes to assume the roles of equipment or local animals. If need be, we had our holomatter avatars.

One key difference between then and now is the amount of cultural research that we did before touching down on a planet. It's one thing to mimic gestures and download language packets, but it's another to appear natural. Things like popular culture, memes, the like.