Longer is better arguments are a total waste of time when longer is not on the table. Many boats have been and continue to be built by home builders that are in this size range and smaller.

Longer is faster and rides better, this isnt a difficult proposal to absorb. I think what you are saying is you expect all the variants and choices are the same length, well they shouldn't be, This is a problem in two parts,

First is what can you afford to spend. In the ratio of pounds per foot a proa is going to win. It only has the narrowest of lee hulls with little in the way for accommodation in it, pretty much half a catamaran. Less pounds equals less money. Add to that these particular boats do with a much shorter materials list, less sail, smaller masts, less rigging, no ballast. Less cabins so for extended periods less crew, less water less battery power,  Less weight is less horsepower to drive it, and less fuel on the same duration.

Weight is a cascading influence that effects everything you can think about with few exceptions. Yet some expences are going to be equal, for example on the same mission requirements electronics, instruments. And so, operating on the same budget will see you get more boat per dollar

The second is how large a boat can you fit in a build facility, this is completely dependent on your circumstances unless you can find a build space and an assembly space for the lee hull. You will find when you need to be creative you will also be including more money as in the first part.

If you can only fit a 35ft hull and your requirements are global with many lucky friends, you are probably looking in the wrong space. If you need a weekender, or something where you will be crewing short handed and are interested in cruising, you feel as though you need to manage the money you have to maximise boat length, a proa should be an outstanding choice.

I wouldn't ever pretend these boats are for everyone, boats are such esoteric animals they mean different things to different folks. But in the practical sense I think everyone should give them a look before they dismiss them