Here's a picture of 3V plugs. I've never changed a set of 3v plugs luckily (only owned 2v 5.4's) but just look at the difference. Judging from where they typically break at, it looks like the lower portion siezes up, and the torque from the thread being so far away from the tip, causes them to sheer off.
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Here's a link with a few more pics, wouldn't let me put the images here...
http://www.denlorstools.com/autoblog/2008/11/ford-spark-plug-removal-tool-picture-of-fords-bad-design/
now look at your 2v plugs, a standard style plug. You don't have the long torque arm between the threads and the tip. It's a very short distance between where the plug socket goes and where anything else could sieze up.
3V plug on left, 2v plug on right
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Now the issue on the early 2v 5.4's was they only had 4 threads per cylinder and the plugs could easily loosen up and spit them. If they weren't torqued perfectly you'd have issues. Too tight and you easily strip 4 aluminum threads. Too loose and you eject plugs. 13 ft-lbs was the magic #. For 2003 they updated the 2v 5.4 to have 8 threads per cylinder and this pretty much resolved the issue.
#7 and #8 are the last on the cooling loop on the 5.4's so they do tend to run hotter, which may cause the 3v plugs to sieze a bit easier, but for the 2v 5.4's you seemed to have pretty even odds of ejecting any cylinder on the 4 thread heads lol.
I'm pretty sure the 6.2's use the same style plug as the 2v 5.4's and not that funky 3v style plug any longer. Ford got a lot of rash for that design and the prone broken plugs on changes. There's even special removal tools just to remove them since they break so easily on the 3V's.
