I think that fact she was cute was entirely the point. Anime love taking cute girls and killing them just to warrant a cheap emotional hook in their series.
Look at Sachi from SAO. No characteristic apart from 'cute' and 'doesn't want to die'.
Well guess what sister? Nor did anyone else in the series, but since your a cute girl, you're easy to get people to like and to emotionally invest in.
I really despise that method in shows. Hence why I stopped Akame ga kill a few eps in.