I think, the producers want to introduce other aspects of the war not contemplated in the PT, for example
-with Even Piellīs death they show a very narrow escape; the Jedi and rank officers like Tarkin are outnumbered
-The dog, hyena or caninus beast that killed Piell, in some way pinpoints the weakness of this character, not of his function on story, but in military terms.
Piell died because the beast bit him in the troath, the Jedi took a mortal wound, impossible to mend the situation.
What happens in that process: the beast uses his weight to immobilize Piells tiny arms, Asoka was occupied with several attackers, she force grab the dog beast too late. (again, itīs a narrow escape with a narrow defense)
In some ways is disgusting Piell only appeared in two episodes, they could have expanded his adventures.
It seems too much in that situation, but Why a Jedi canīt use a force lift without the aid of his hands?
Piell could geminate or mimic Yoda in some aspects, but his power is less significative.
I am not at currant with Pt EU novels, but in this series of Clone Wars, where "only the strong" are surviving, Yaddle is the next candidate to die in that way, too.