Thanks for asking this. To me this where we come to the crux of the matter. We need to make the path practical. The question of why outlook matters, on the personal level, is what right view is all about.
So far as rebirth is concerned, these are some of the ways I make it matter in my own life.
Rebirth reminds me that most things in this life are like borrowed goods, to use the Buddha’s simile at MN 54. It all has to go – at the latest when we die, but often much earlier. This includes our material possessions, our friends and family, our physical body, but also all aspects of our personality that are tied up with this world, such as our social status, our education, our sense of achievement, and any other aspect of our sense of identity that relates to this life. There is not much left! The one thing that remains as you move on to another life is the quality of mind that you have developed in this life. Create a beautiful mind in this life, and that’s what you take with you. The idea of taking a bright, joyful, and wise mind into the future is extremely appealing to me, and no doubt to many others. (And, as an aside, to me this is really the essence of what kamma is all about.)
I have often seen the counter-argument that cultivating our minds is the right thing to do regardless of whether there is rebirth. I can only agree with this. The point, rather, is that adding rebirth to the equation dramatically alters the balance of our focus. If this life is all there is, then it is reasonable to emphasise achievements that belong to this life. In other words, enjoyment of the immediate pleasures of this life carry a lot of weight, especially since most of us do not know the extent to which mental development is possible. If we doubt our own ability to change our mental world for the better - and most people would have some degree of doubt about this - then focusing on the more tangible pleasures of this world makes eminent sense. With rebirth the emphasis changes from what we achieve in this life to how we achieve it. It is the how that determines our mental development, whereas the what is the borrowed goods.
This does not mean that we don’t care about this life. On the contrary, it means that we deepen the care considerably. If the how of life is what matter, then our every act becomes important. Circumspection and mindfulness in all our activities, including our thinking, becomes what our lives are all about. It draws us into the present moment and actually makes us more alive. In the end it increases our quality of life far more than living according to YOLO. The problem is that it is very difficult to see that a strong emphasis on mental culture is the best way of living. Rebirth helps us reorient in this direction, often powerfully so, as can be seen from the sutta similes given in the OP.
For many the above is probably enough for rebirth to play an important role in their lives. But there is another aspect to rebirth that is more profound and more difficult to see. This is that rebirth is inherently suffering. At AN 10.65 Ven. Sāriputta defines suffering as rebirth. Part of this is that saṃsāra has no purpose. Our present lives tend to feel purposeful, but from a saṃsāric bird’s-eye view this is an illusion. We are not actually going anywhere; as I have mentioned above, it’s all just a bad version of Groundhog Day. So there is a discrepancy between how we feel about our lives and the overall reality. Having the right outlook is about reducing the distance between how we look at the world and how the world actually works. Seeing things rightly, or as rightly as possible, is a prerequisite for making wise decisions. When we see things rightly, life regains its purpose, but it is a radically different one from what it used to be. Making an end of rebirth becomes the purpose of existence.
