One “can” live without the plate between the trackpad & the batteries but do you really want to run the risk of the battery rubbing itself open? Without Apple’s plate I’d still look to find a thin plate that I’d adapt to protect the batteries.
This is poor advice, not firmly securing the battery runs the risk of them moving in case of a drop and the Mac catching fire like a Samsung Note 7.
As Jeff suovanen states on the rMBP Mid 2012 battery replacement page in the comments:
Because of the dangers they present, lithium-ion batteries need to be firmly secured. In the absence of any [http:///Anleitung/MacBook+Air+13-Inch+Mid+2013+Akku+Austausch/15205#s49235|screws or brackets to mount the battery], you need to use enough glue to make sure the battery’s not going to come loose across a broad range of user behaviors and environmental conditions over a long period of time, plus a margin for safety. Bottom line, if it’s designed to use glue, then that’s what we’re stuck with.
Score another successful replacement using monofilament to remove the outer 4 battery cells without dismantling the Mac making this a fairly easy fix.
The warning about needing to be careful about the keyboard ribbon cable on the center two cells led me to be more cautious when removing them as there are no pictures showing the Mac without the batteries to more clearly identify the risk. As they are far from the speakers I used the acetone+cards inserted from the sides to weaken the adhesive & remove them. Now that I’ve performed the replacement I see that there was no danger in using the monofilament to remove the middle two cells either.
It took me longer to clean up the remaining adhesive strips and then the remaining glue than every other step. I found that for the glue traces, rubbing alcohol worked better on the aluminum & acetone was better on the bottom of the trackpad.
What so you think that a removing the optical drive which weighs less than a AA battery will unbalance a MBP making it unusable? LOL!
Unless you use the MBP on a high wire (an even then I have my doubts) you'd never notice the weight difference.