They do it to ensure a high standard of safety. That no criminals with fake identities and falsified documents use their brokerage services for illegal money laundering activities. So that they remain a clean company operating within strict Swiss law. So that they don't lose their license (which could lead to problems for all customers including you).
As I said, some of us prefer a more serious company and regulation to put our hard earned money in. If you don't like that and instead prefer some crappy bucketshop operating within a regulation that is basically a joke, then feel free to put your money there.
Strict identity verification can be tedious but there's a good reason for it. As a trader you ought to learn patience.