ATPL is a necessary requirement for most Command positions on multi-engine helo's.
If you are not interested in Multi work then it is probably not beneficial to get it. However, as a professional aviator it is good to learn as much about your occupation as possible and the ATPL further extends your knowledge.
With some management and upper level company positions an ATPL will add weight to your application and lately in OZ it is often one of the minimum requirements for general job applications.
Merry Chrissy