A lot of my favorite characters have been killed off in TV shows and books before. It's sad when that happens, but that's not what's important. What's important is how the series carries on without them, that the series acknowledges their death and that the surviving characters respond accordingly. Characters, especially in literature, don't get killed off arbitrarily. It's not like they killed her because Kate Mulgrew was unavailable to play the part, and I very much doubt they killed her because they just didn't like her very much.