^'no direction to further take the character in.'
surely you jest?
It's a polite way to say they had no interest in writing for the character anymore.
They openly admitted to writing the character into what they felt was creatively a dead end.
I thought it was fairly obvious that after "Caretaker" they had no soild direction on what they wanted Kes to do or become.
Yes this is a hilariously transparent comment. Lien had an impressive screen presence and that voice...

but, in spite of giving her a very limited life span and nebulous powers that could have been developed over time (instead of instant switch on and reset button) the writers had no idea how to use her in the plot on a regular basis. There was a significant disconnect of imagination on the writers' part that had nothing to do with the actress or character. If they had ripped off the Dark Phoenix saga or the Fury and told the story as an ongoing plot thread it would have worked perfectly for Kes.
If they had developed her powers there would have been a myriad of ways she could have contributed and her death should have been part of the overall plot arc from the start. She had more plot potential than Harry, Paris, and Chakotay combined if you remove Belanna from the Tom equation.
At the very least they should have kept her around until after the Year of Hell and used the temporal energy as a way of writing her out... taking Harry with her!
In fairness to Harry, he wasn't given much more of a chance than Chaokotay. I would have been happy to see more of the twins and his attempt to woo the wrong one - maybe even ending up with the right one.
I also thing that the rebellious maquis from season one should have appeard more often - only Chell got to make a comeback and then I think that was only in the final season. Gerron would have made an ok field medic after all.