I agree with Gasket, but if you want a in-universe explanation that makes sense:

 

Reformatting it every few seconds is not a smart thing to do, for several reasons.

 

1 - Reformatting requires a lot of energy. That is logical, since all the different parts need to be reformed and reshaped.

2 - A Transformer's body is a weapon. It is a tool, a finely tuned one. Getting used to a body and managing to use it to its optimal efficiency can take a while. Doing so in battle would be counter-effective.

3 - Reshaping one's body increases stress on the material. Compare it to a piece of lead that is being bend. The first time, nothing happens, because the material is flexible enough to handle it. Yet, if one keeps bending the piece of lead, the stress on it will eventually lead to it breaking. Something similar would occur when a Transformer reformats too often.

 

Bumblebee apparently figured the friendship of Sam, and by extension, Mikaela, was worth the costs of reformatting. Why, I would not know.

Bumblebee apparently figured the friendship of Sam, and by extension, Mikaela, was worth the costs of reformatting. Why, I would not know.

Maybe he wanted to sniff his own seats...

I guess it makes sense what Zak's trying to say -- in Beast Wars/Machines, the reformatting seemed painful to the TFs, not to mention they had to adjust to their new robot/alt. modes, which took them some time. I guess I meant they could reformat as a last-ditch effort to save yourself from being blown away.

 

BTW Bumblebee only reformatted so they could show off the '08 Camaro, we don't need no stinkin' canonical explanation for that one

There are in story reasons for things and out of story. BB changing to the O8 is a marketing decision. It was not for or justified by the story. In fact it was contrary to the in-story reasons, as evidenced by this discussion. In general the quick reformat ability was just to introduce the autobots quickly. It is one of many halfassed things it was hopped would slip by without anyone noticing. In general it worked. It was done quickly and effectively and while I think it was a poor choice most audiences will never notice it, so I can't say it wasn't well executed.

I see reformatting for movie Transformers the same way a human changes pants.

 

If I stab you in the side, and you change pants, guess what? You're still hurt.

Same for TFs.

LOL, funny analogy, and good point, I s'pose.