[quote=@Stern Algorithm]
In the original Beast Wars, the cybertronians had to take beast forms because it protected them from 'energon radiation' or something. Is that going to be what prompts our characters to take on beast forms as well?
[/quote]

Though it's canon-icity is dubious, Beast Machines (the follow up series) did portray/suggest that there was some precedent for Beast Modes- a new character introduced in the first season of that series had been the only survivor of another exploration mission, and fallen into similar circumstance (stranded on a planet and unable to remain in bot mode indefinitely). However, the lifeforms were exclusively plants, even the ones that run around and behave in animal like ways.

So, I guess it's not [i]that[/i] hard to imagine, but it wasn't common.