By rooting and deleting apps , or any other modification of the /system partition, you are making it impossible to apply any patch released by the manufacturer (it is a binary delta of the volume).

Consider disabling the apps; if the manufacturer doesn't allow disabling the app through Settings, you can always do it via adb. When you disable the app, the system will ignore it and behave as if it wouldn't be there. You can't get any additional benefit from the deleting, you won't gain any additional free space, as no app can write to /system partition for the above reason anyway.