A healthy organization should have one, in my opinion. Management being against it is an unhealthy sign.
Just so you have some context. a Works Council has the following rights:
Right to discuss: they will have a bi-yearly meeting with the employer, who will report to the employees the financial situation of the company
Right to give advise: (This is the one startups find scary). When a company wants to do an investment round or any action that has economical or organisational impact, they _must_ ask for advice from the Works Council. The employer _must_ take their advice into account. If he does not, there is a cool-down period of a month before the decisions comes into place. Within that month the employees can take the employer to court in Amsterdam to block the action. This basically means employees have the right to block investment rounds through court. The burden of proof is on the employee that this is not in interest of the company.
Right to vote: The WC has the right to vote on certain decisions regarding reduction of working hours or work conditions. Here the onus is turned around compared to the right to advise. The WC makes the decision, and the _employer_ has the right to countersue. This basically means the employees have the right to force the employer to court if they want to do a firing round. The employer's task is to prove in court that the firing round is needed by law.