Personally, I would use those almost interchangeably. There is a slight difference in connotation, where the first sentence (using 'would') makes it sound like you have/had an opportunity to change the situation, by chose/will choose not to. For example, if you're planning on moving and one house that you're looking at is close to your parents and the other is far away, "My parents wish we would live a bit closer to them" would be a perfect thing to say if you were talking about the decision on where to live. This sentence also has a slight hint of dissatisfaction as you pointed out, where your parents have a slightly negative attitude towards the distance between you and them. The sentence the textbook says is just stating a fact; your parents wish you lived closer to them, but you don't. There isn't really any kind of underlying tone that I would pick up on there.