That is how your camera manufacturer has designed their system to work. They have designed their lenses to be small and light in so doing they require that distortion correction must be made using the software. The correction is also done by your cameras firmware when processing the raw data to create the in camera jpeg. The lens correction info is provided in the raw file capture, so Adobe and other third party raw processing software providers can make the required correction.
You can if you wish post a feature request at the official Lightroom Bug reporting and feature request forum