Well, Uber Black is the properly licensed service with professional drivers and properly licensed and insured cars. It's in operation and not affected by this injunction. There's some nitpick about whether they should or should not be allowed to pick up people from the street, but that's minor.

The service affected here is UberPop that allows any private person to use their private car with domestic insurance to pick up people and transport them commercially. Uber has decided that this is the market they want, but that's just not legal in germany. Private persons that want to just earn a little on the side won't spend the time and money to pass the test and get commercial insurance. Since UberPop targets private persons it's also an invitation to tax evasion, but that's a different issue.

Uber could restrict themselves to the legal business model but have chosen not to.

There is a barrier here and it separates the people that want to be professional drivers from the non-professionals. The professionals are allowed to transport people for commercial motives, the non-professionals are not. This separation exists in a lot of areas, for example when producing and selling food, construction work etc. If I want to provide a professional service that has an associated risk, I must pass some certification that shows I at least roughly know what I'm doing.