I think these modifications could have been discussed a little before than 2 days before to final submit, because some of us don't have too much time to change more code. We understood that mobile base was needed in task3 in order to be able to pick and place far objects, but not 'illegal' to use in task1-2 because real robot always have a mobile base.
I would agree with that decision, because is other way to understand these task descriptions, but not 2 days before to final submit when we are in extended deadline.
Regards,
Luis Rubio