I thought the character was interesting to begin with, she was something different. It was different to see a character that only lived 9 years because every other species on Trek has a longer life span than humans. It would have been interesting to see someone's whole life played out durring the run of the show.
But other than that she wasn't that unique, her short lifespan was the only unique thing about her. Pointy ears, mental powers, that's nothing new in Trek
If they'd actually done something with the short lifespan, it would have been interesting.
Say they'd made her lifespan 7 years. And then aged her year after year.
You'd have a character who lived a full lifetime within the seven year series. Would have been interesting to see if Jen was up to the challenge.
However, according to some this is a horrendous idea, because how dare I suggest that aging & dying is a part of living, and something that would have repercussion on all of the characters.