This is the power of free software. Users get the source code so they can fix the problems or introduce features. Also, we can share the modifications with others so that everyone gets the benefit of the development.
If the software was nonfree, this was not possible. We had to beg the developer and even then there is no guarantee that the developer would fix it.
For people who care about, support, or build Free, Libre, and Open Source Software (FLOSS).