Although I was sad she died - and too young to die, or seemed so anyway - I'm not sure there was much more they could do with the character. I know some people won't agree with me, and admittedly I've only ever seen one episode of The Sarah Jane Adventures so I can't give a fair judgement really. But I wasn't partiuclarly expecting to see her back in Doctor Who.
Nevertheless, very sad to see her go, and she left a terrific legacy with the Doctors she accompanied. One of the best. Farewell, Elisabeth.