Easier paddling is more boring to some
If you are talking about making long, open-water crossings on a big lake, fully decked boats do have definite advantages over an open boat. Chiefly the relative immunity from big waves, the availability of a solid brace on both sides, less windage, a higher paddle cadence, and (assuming one has a reliable roll) a method of self-rescue that leaves one "good as new" upon completion.
That's not to say that experienced open boaters can't safely make long, open-water crossings though. Paul Conklin, Harold Deal, and Gary Marble paddled open canoes all the way across Lake Ontario.
As for "ease of paddling" many find the greater variety of strokes used in open boating to be more stimulating than the largely symmetrical and fewer strokes used by kayakers. The card game "war" is easier to play than contract bridge but many find "war" to be less than engaging.
Some people with bad backs simply can't tolerate long periods of sitting in a kayak. In addition to easier entry and exit, canoes allow the paddler to shift around quite a bit more, and quickly accessing items in the boat is much easier in a canoe than a kayak.
As for the gear storage issue, for what it is worth, I have paddled a variety of kayaks with bulkheads and hatches and all of them have taken on at least a bit of water so I'm not sure your experience is typical. Canoes allow somewhat more flexibility in packing options than kayaks. I haven't seen a sit in kayak that would accept a 60 L barrel, or even a 30 L barrel for that matter. If one is only expecting to pack and unpack the boat once or maybe twice a day, I don't see this as a big issue but if conditions require loading and unloading multiple times a day, and especially if portaging any distance at all is involved, then the canoe has a distinct advantage.
Can't get a decent tan on your legs in a SINK.
