I have no idea, but I guess that it was built because it was technically feasible.
Xgl [1] was released in the same year and had quite similar capabilities [2]. Xgl, in turn, lead to Compiz/Beryl which is the technical ancestor of the most popular window managers we run on Linux desktops nowadays (e.g., Kwin in KDE).
So to some extent, we still use the tech which was developed back then, the effects are just a lot more subtle.
Xgl [1] was released in the same year and had quite similar capabilities [2]. Xgl, in turn, lead to Compiz/Beryl which is the technical ancestor of the most popular window managers we run on Linux desktops nowadays (e.g., Kwin in KDE).
So to some extent, we still use the tech which was developed back then, the effects are just a lot more subtle.
[1]: https://de.wikipedia.org/wiki/Xgl
[2]: https://www.youtube.com/watch?v=-CgqWlX_GsI