CIS tells you what to do.
I131 is Advance Parol Application. It is mandatory for all 485 pending applicants who will make foreign travel, except for those who are on H or L visas. Even for H or L visa holders, it is much more convenient to have AP before travel.
There is another for I765 for Employment Authorization Document (EAD), you will need it if you are not authorized to work otherwise.
But you don't need I131/I765 if you don't want to make foreign travel/work.