These two classic Alienware laptops have reached End-of-Life (EOL) status in order to make room for the thinner, lighter, and sleeker Alienware m15 and m17 successors. The Alienware 17 in particular is being succeeded by both the Alienware m17 and the much more versatile Alienware Area-51m desktop replacement.
https://www.notebookcheck.net/End-of-the-road-Dell-will-cease-production-of-the-Alienware-15-and-17-series.386491.0.html