The main purpose for Taurus is to hit nuclear missile silos. So it is design to be stealthy and accurate with a decent warhead. However that also makes them really expensive. So Germany does not have too many to begin with and most of them are actually needed in case Russia actually might go nuclear.
For Ukraine it is not a terribly useful system. Striking nuclear missile silos is pretty useless. Most other targets can be more easily served with a more conventional and cheaper Shahed like drone too. It would be better for Germany to deliver licensed built or self developed long range Shahed like drones in large numbers.
Limited resources. Giving Ukraine Taurus costs time, money and other resources. If those can be better used for another system, then that is the better option.