It helps to ensure that your gas cylinder is properly filled at the re-fill station whereby you know by inspecting the full limit gauge when gas is filled by supplier.
The gas regulator helps to detect cylinder leakages and automatically stops the flow of gas to the cooker to prevent wastage and fire outbreak in homes.
Finally and most importantly, it helps to monitor the level of the cooking gas with the attached gauge so your gas does not get exhausted at odd hours or in the middle of cooking dinner/lunch/breakfast. It saves you the embarrassment of looking for an alternative