I may be weird, but to me, the definition of a "small ship" is one with fewer than 500 guests max double occupancy. These are actually my preference. My next cruise (if you can call it that) will likely be on a chartered catamaran in the Caribbean that has a max occupancy of SIX guests! Now even I may find that a bit small -- we'll see.
But you can imagine how I feel in light of my preference for ships of 500 guests or less, when I know that NO LINE has any plans to build any ships in this category. So when the existing small number of these ships has to be retired due to old age, my favorite category of cruising in terms of ship size will be forever gone.