Shorties seem pretty common as the only choice in many rental pools in tropical locations all over the world. They're cheaper to stock, easier to fit a variety of people when you don't have to worry about the arms and legs, and sufficient to do the job for most visitors in those temps.
In tropical waters, a fullsuit of some sort is great to have for abrasion/critter protection, and will feel nicer when hitting water that's a little cooler than you'd like. But what's on the core is probably more important for keeping someone warm over a number of dives. That's why they make shorties and vests and things of that sort. I agree not to overthink it too much - if they think they need more, I'd get a fullsuit of some sort that fits decently and be done with it. Doesn't have to be that expensive. Besides neoprene, you might want to look into things like sharkskin, lavacore, or suits of other polyolefin type layered materials for even better packability. Then if they need still more than that, rent a shorty there to layer on top. This has the advantage of having something between you and a peed in rental.
Personally, I find hooded anything a pain and uncomfortable - I dive warm water to avoid hoods! Seems like overkill for tropical waters, and you really don't see people using them that often.