There is a reason for that.
At the school where I teach the class, the workshop is fairly small and is in the basement of the building. The basement is reached via a set of stairs from a lobby and you have to make some fairly interesting turns to get a strongback down into the shop. Across the parking lot from the building is a small barn. In this barn, we get to store materials and boats in progress. This is important as we cannot leave the boats in the shop during the week as it would interfere with other classes, and it would be too difficult for my students to schlep their materials back and forth every week.
The Wee Lassie is about 11'-6" long and the Wee Lassie II is about 13'-6" long. Both boats are 28" wide. The Wee Lassie II gets down into the basement with a bit of difficulty. Once all the material has been milled, we move aside some of the power tools and can just fit 6 canoes in the shop to work on them.
I've had a student who purchased plans for a Newfound Woodworks Osprey kayak. It's roughly a 16' long, 24" wide kayak. I have real concerns about getting the boat in and out of the shop. Also, because of the differences in the form from a canoe, I've got serious concerns about storing it. It's a neat project, and I think it would be fun to work on, but I think it is too big and too "different" of a project to try to wedge into the class. I worry that it will be a distraction. Kayak builds are also much more involved and I don't think that the student could finish the boat in the allotted time. I've got some plans for some smaller kayaks and would like to propose them, but I still think that building a kayak in a class for canoes would still be an issue.
OspreyI have yet another student who purchased plans for a Sandy Point Boatworks Bufflehead canoe. At 14'-6" and 33" wide, it pushes the limits of size, but not technique. We'll have to see if we can fit
If you're tempted to build a cedar strip kayak, I highly recommend Ted Moores' book Kayak Craft - a thorough study on the subject. Also, Newfound Woodworks and other sources have great DVD's to walk you through the process.