US immigration rules would be much saner if people born here had to jump through the same hoops, wait in the same lines, fill out the same forms, and go through the same process for citizenship, as people not born here.
You're missing the point. Birthright citizens have nothing but "geographic location of birth" to qualify them as citizens of their country. They literally (in the real meaning of 'literally') did nothing to become citizens. Their children will also likely have to do nothing to become citizens, as long as they're born within the same borders. What motivation do people who expended zero effort to become citizens currently have to help or vote to make immigration rules more sane?