Aside from that, it just makes for a better story. They wouldn't want to hamstring their ability to write action scenes because of some line from the first season.
So, I have a story about Star Trek the Animated Series.
My friends and I used to watch it in college, but it was a drinking game. We watched it in Spanish, with no subtitles (and none of us speak Spanish). And there were certain things they said every episode, and everybody drinks when they say it.
Such a shame with Kes too. Fantastic actress, badly designed character, poor planning. Wasn't her fault.