Hummmm that's interesting John.
Maybe the ones I have looked at used are being sold because of that reason. I have never been to a kayak shop and as far as I know, there isn't one in those whole state. So other then the 2 new kayaks my wife bough from Old Town, I have never even seen a new kayak. But I have now seen about 25 used ones for sale and in fact have bought several of them for our little fleet, so we can loan them to the kids and parents who want to try kayaking with us.
But so far I have yet to find a "barge" or "freight-liner" for sale. The roomiest one I have ever seen or paddled so far is the own I own, the Necky Chatham17, and it is large enough for me and fit me pretty well, but if my feet were much larger it wouldn't and I only wear a 9. I have thick legs and I found the thigh braces were a bit short and only hooked over to about 11:00 on my left side and about 1:00 on my right. So it certainly was not too large in the area of my legs and feet. EVERY other sea kayak I have looked at is smaller then my Chatham. But I have never got to see any new ones. 2 others I bought for friends and brought to Wyoming recently are 2 Perception kayaks, one at 16-1/2 feet and one at 17 feet. Both are good fits for me but neither had any extra room around my toes. I fit into them, but the area over my toes was very close.
What I am finding I like is a close fit on my whole lower body from lower back to knees, but with room enough to move my feet at least 1" up and down. I can in my Chatham but only about 1/2 inch.
In my wife's Wilderness Systems Piccolo I have to point my toes forward and can't let my feet relax. Yes, I know it was made as a small persons kayak, and so I can forgive the lack of room in it for my feet. I am short at 5' 6" but I am not "small" I weigh 190 pounds. I still can use it well, and it's a fast and easy kayak to paddle and maneuver. My wife is tall at near 5' 11" and had long feet for a woman, but she can get into the Piccolo and her toes touch the deck when her heels rest on the hull. She is slim at 145 pounds. She cannot wear any shoes at all however, unless she also points her toes. I have to point mine even barefoot. It could have been made with a bit more room over the foot section and not suffered in any way ----- as far as I can see. We both like the close fit of the rest of the boat. It's easy to edge and turn, and very nice for rolling.
So in the future I hope to make some kayaks and I'll make them for individual owners, but one thing I can't see any down-side to is simply making the deck a little higher only over where the paddlers toes will be Such a clearance can't hurt anything as far as I can see. Am I missing something there? Is there any reason a clearance of about 1 to 1.5 inches over the toes would hurt? If I were to make the deck swell up about 1" over the width of the deck and about 8" back to front I am only talking about adding a very small amount of internal volume. As far as I can see the foot braces only adjust about 1 foot anyway, so having room behind the rearmost setting of the pegs is not needed, and would do nothing at all for the use of the kayak or any handling benefits. The ONLY thing I want to add is room for the toes of the paddler.
To all those out there that do have experience in kayak design; I am very interested in what I can learn from you.
One thing I like about the idea of building is the ability to actually fit the sizing to the owners. I can't see much wisdom in re-designing hulls. I am sure that is something that's been perfected many years ago. The deck and seat, back bands, thigh and hip braces, foot pegs and foot room could all be adjusted to individuals without modifying the hulls much. If I was to set myself up to make 3-4 different hulls, (narrower to wider and shorter to longer) I believe I could finish a kayak to fit almost anyoone. ( I think.)
Am I wrong?