(TL;DR they give us easter eggs, concept art, and in movie designs that are flawless, but then will have a character be a completely different person but with the same name.)
Explanation: more specifically, why do the live action transformers movies have concept art, and actual in movie designs that are literal perfection of the character like in the beginning if the bumblebee movie, and then drastically change it to something different? Or on the other hand, we get this drastic design change, but there are still easter eggs to the original design, like when rotb mirage showed he could turn into a racecar, or when in the final battle wheeljack had his ears for a split moment. 
Not saying i dislike the designs or anything, personally rotb wheeljack is my favorite design. Yet why do they show that they could make the characters "perfect" to put it dramatically, and then make a whole new character essentially with the same name. The only one who is ever consistent (usually) is optimus because hes optimus. 
In rotb if you didn't know who they were, i bet only the maximals beast modes, optimus, arcee, bumblebee, and unicron would be the only characters you'd recognize. Nobody else looks like their characters.
Its like when they come to earth they are a whole new person. Talking about bumblebee movie bitzwing specifically here, everyone on cybertron was mwah perfect😙👌 but then on earth blitzwing is a regular seeker? Like still i'm trying really hard not to complain, again i really like the designs almost every time, but why do they show they could do it and then don't. Is it just "creative liberties" and "new takes?" Honestly its still very cool usually, the movies and designs/story, just more confuses me. 

Why do they change characters so much but show they could keep it "accurate" if they wanted to?