The screen/strainer is there to keep any particles from deteriorating pipes from getting into the fill valves on the washing machine.  This is mainly a concern if your house has galvanized pipe as opposed to copper.   You can find large laundry hose washers with an integrated screen at any hardware store that will serve the same purpose as the plastic thimble.

The strainer isn't meant to be a flow restrictor, but in older homes like mine with 90 year old galvanized pipe, it can function as one if it gets clogged with debris.  It's the same with aerators on your kitchen and bathroom faucets.