Why are these heat pumps so large?

True. A lot of the older units had all the components outside the coil in a separate compartment. Lrge cabinets with relatively small coils. Now most have all the components nested inside the taller coils, very little casing, mostly high efficiency coils. Last time I upgraded a half ton, the condenser unit got a smaller footprint but grew about a foot taller. Gerry, I know what you are talking about. I was at a condo the other day, every unit there was a different brand, sizes all over the scale and mixed components from inside and outside and none marked to identify which unit it belonged to. Naturally, the sh*ttiest one there is the one you have to inspect.