As the first animated series focused on the X-Men, the creators of this show had plenty of inspiration to draw from and could have began chapter one however they pleased. Introducing the characters and having them defeat the villain of the week would have had kids plenty excited.
Instead, they opted to let the X-Men hit the ground running.
The dual Night of the Sentinels episodes were excellent ways to introduce us to the series, but the second part is intense for a cartoon. After saving Jubilee and successfully infiltrating the Mutant Registration Program facility, it looks like we're headed to a happy ending.
Beast is captured and Morph is killed. Dispatching a character early in a series is a bold move even for an adult show. Killing off an X-Men during episode two of a children's cartoon is intense.
This set the precedent that no X-Man is safe and that the series wasn't afraid to subvert expectations to tell a great story.