Modern calligraphy is not impossible to practice, but most of it has embodied modern styles and schools, and its charm is very different, which is very different from ancient calligraphy schools.
It makes sense to practice ancient Chinese characters. The purpose is to hope that you can inherit the origin of this ancient art. Of course, if you only need to write beautifully and don't want to learn calligraphy as a major, then modern famous calligraphers are also right.
In fact, your teacher hopes that some of his students can truly inherit and carry forward the ancient calligraphy art and become a major in teaching it. The problem is that his expectations are too high. It is difficult to find young people who value the ancient calligraphy art now.