pretty important, it is there to filter out debris from getting into the fuel pump, injectors, and fuel lines. Without it you are asking for engine performence problems. I know this is not what you want to hear, sorry.
The fuel pump screen is attached to the in tank fuel pump to keep debris from entering the fuel pump. If you don't want to mess with it you do have another filter on the car that will protect the rest of the engines fuel system. But sadly the fuel pump will have no protection. I would recommend replacing both the fuel pump and the fuel pump screen while you have the tank down it is very labor intensive by your self to drop a fuel tank not to mention dangerous. Good luck. Why did you drop the tank to begin with what kind of problem lead you to drop the fuel tank?