WordPress unlimited plugins is a great way to save money and get constant updates and support with monthly or annual fees. Plugin developers often use this business model to develop their products faster, because this model allows them to earn more. This also encourages developers to introduce new features as well as get premium support.
This is a great investment if you are an agency and you often need to provide clients with some plugins. This reduces your costs compared to buying licenses for a limited number of sites. And it allows you to set a reasonable cost for your clients to maintain your projects. This reduces the risk of viruses and removes your responsibility because you can call for support at any time.