I also think that you can tour on almost anything if you put your mind to it and since most people don't get to try loads of touring bikes they simply develop a preference for what they own. If you could own one of every major touring bike and ride 'em 365 you'd probably determine that a few stand out for you and your needs.
It's also possible that the message here is that, to quote some really stupid teen flick from years ago, "It just doesn't matter!" Most, if not all, touring bikes sold today are adequate for the purpose, and after riding 4-10 hours a day for a week or two, most riders get used to their quirks. Not trying to get all preachy here, but I am trying to point out that most tourists go for the ride. It's all too easy to get tied up in knots while armchair shopping -- Bike A has oversized tubing, but Bike B has increased trail, etc. Once you get out on the road, though, the slight toe overlap disappears, you learn how to damp a slight shimmy, or whatever; and you'll get more interested in "What is that flower?" or "Why don't they fill the crack in these $*&? expansion joints?"
Thankfully winter is almost gone here (daffodils blooming, frogs peeping, and I saw the first mosquito of the year yesterday), so it's time to turn the computer off, put away the glossy catalogs, and go ride.