Basically, they need to release a second Matrix with some of these guys. One that doesn't fit inside guys' chests.
Because the ones we're getting are more or less properly sized.
Exhibit A:
Yeah, Prime's fingers ain't fitting in those holes. That thing changes size.
Even in the smaller Hot Rod's hands:
And remember -- he grows BIGGER to become Rodimus Prime.
Everyone's always like "Ultra Magnus/Galvatron couldn't open it because he didn't use the finger holes!"
But nah. Their fingers weren't fitting in those holes. That thing just grows big when it needs to.
Oh, wait...
Eh... maybe?
I dunno, still don't think they'd fit here, even if that thing got way bigger. Optimus was palming it above, and the larger Ultra Magnus probably couldn't do that with it here.
Anyway, this is all to say that I think the ones that store in their chests are properly sized -- for that. But not for being opened. You need a separate one for that, if you want to maintain any sort of semblance of screen accuracy.