actiondiver, I'll bet it's because 4WD owners take it for granted and 2WD owners don't know what they're missing.
I would suspect that the pro 2-wheel comments stem more from geography and/or typical useage than just because one owns one. If it's always worked for you, it stands to reason that it's a logical choice. For 90% of the time I happily use 2WD. It's that other 10% that are the sticky point. If you live in areas of the country that get heavy snow or use your truck for more than highway/gravel road transportation, you may find a real use for four wheel drive. There are places I go in Colorado that you would be hard pressed to reach in a 2WD in the best of conditions much less in muddy, snowy or ice packed conditions. A 4WD can allow you to keep going in conditions that stop a 2WD and will not necessarily get you stuck worse as has been mentioned. It is simply a matter of knowing both your and your vehicle's limitations. There are times when you just need to turn around.
I have a stock 2001 Chevy Silverado Z-71 with IFS and AT tires. No lockers, no lifts, nothing extravagant as it is a daily driver. It cannot go places that the custom (and trailered) rock crawling rigs can go. Nor can it always go the same places that a lifted rig with dedicated mudders can go. However it can go MANY places you simply can't get with 2WD. The thing is, I am familiar with going offroad/rough trails and familiar with my truck. I check out the trail before I drive over it if I can't tell how bad it is before I drive through an unknown obstacle. Like anything else, it's a matter of knowing what you're doing and while no expert, I haven't had to call in a tow truck in the past 15+ years of four wheeling.
The extra expense I've incurred over 90,000 miles with this vehicle are only the additional cost of servicing the transfer case and front differential so I don't fully buy the cost argument other than the initial vehicle cost. Perhaps when it comes time to replace the transmission I'll feel differently but given the use I've made of the 4WD so far, I don't think it will hurt that much. As to gas, I don't think I get significantly worse mileage than a comparable 2WD truck. Although you are carrying more running gear, you're still running in 2WD for the majority of use. I get about 16 mpg around town and 18-19 on the highway. I haven't heard of any full size half-ton extended cab pick ups with V-8s getting a whole lot better than that. If you're looking at an older Toyota four cylinder, you'll obviously do much better in that department.
I think the point about a 4WD getting you into more trouble might be valid but only as it rates to an inexperienced/uneducated driver and as it's not rocket science, that is a problem easily remedied if a driver wants to. I've certainly been stuck and expect to get stuck again but I never would have had the opportunity to get where I was or would have been stuck much further down the trail if I'd been out with a 2WD. If the argument is that a 2WD will keep you from getting in trouble then that is in large part because you won't be able to access all the areas you can with a 4WD and such grand opportunites to get stuck. I'll take the access myself rather than the limitations.
On the whole bug out thing, I tend to agree with the idea that you're going to have trouble getting out at all unless you can take to the air or something. That said, if I were setting up a vehicle designed to get me out in desperate circumstances and unknown conditions I think I'd want the most capable one I could afford.