Every design involves compromises in order to try to find the best for a particular application. Take airplanes for example, which actually relate well to bows in some respects. Heavier airplanes with longer wings and fuselages, and with more dihedral in their lifting surfaces tend to be more aerodynamically stable than lighter planes with shorter wings and fuselages, and with less dihedral. I won't go into all the reasons for these effects, but one of them is moment of inertia associated with the rotating mass of the aircraft, which has also been described here by others as it relates to bows and tight rope walking poles. The aerodynamically stable planes resist departure from the current flight regime and will tend to return to that flight regime in the event there is a sudden force that causes a deviation. That stable design is great for planes that are in cruise for long periods of time, but it is a terrible design for planes that need to be maneuverable and quick. Similar design factors exist for guns and bows. A benchrest rifle with a long, very heavy barrel is great for shooting off a fixed rest at a stationary target, but it would be terrible for most deer hunting situations. For most hunting situations, a gun that is lighter, more maneuverable, quicker, and shorter is a much better weapon to use.
Who wants to be shooting the most accurate, most stable bow possible while hunting? I sure don't!! That would be a very long, very heavy mass, very light poundage bow with all sorts of stabilizers and wrist straps, and definitely adjustable sights. I would have to stand with the bow completely vertical (a bubble level would help with that) and have exactly the same body position as I had practiced from thousands of times before. Obviously, none of us want to, or even can, hunt like that. So now we are talking compromise. The compromises will be shorter bows, less mass, and higher poundages.
To make short bows (58 inches and less) more stable and create a geometry that will produce a lower string/tip angle at longer draw lengths, a more forward, deflexed riser is helpful. So is the reflex/deflex or recurve tip limb design. With more recent design and material advances, we can have short bows with smooth draw and good shooting characteristics, while also getting the handiness, quickness and maneuverability that short bows with less rotational stability provide. That is why Ron can talk about how good his Shrew bows shoot, even in the shorter lengths (down to 52"). Shrew makes the Model T for those who want the longer target bows that can still be used for hunting, but the shorter Shrew bows tend to be better for more hunting situations. If you don't believe me (or Ron), then try one out and see for yourself. I did, and it is hard to go back to my dozens of wonderful, longer bows when I head to the hunting camp. Of course, there are other good short bows besides the Shrews. The Shrews just happen to be some of the best and the most well known. If you can locate one of Big Jim's Thunderchild bows, or a Treadway Black Swamp, or one of the short Black Swans or another top quality short bow of modern design, try one of those to see what one feels like. Remember though that all short bows are not created equal.
Allan