To stop agencies keeping employees as temporary workers indefinitely, being discriminated against all the time, with no rights to complain.
There should be a term (3 months after starting a new job) when the company must decide - if they like your service or not and you will be employed as a staff. It should not matter if you are part or full time.
Why is this important?
This is important for keeping the human rights and dignity, is important to stop these agencies making money from doing nothing.
There is a lot of humiliation working as an agency staff - they make you work hard with no reward.