There's not thing the right tool can't get them out, just need to have patience. Replace them with new upgrade ones and you'll be all set for another 100K miles.
There's an entire tool set for removing the broken plug from the vehicle when you've snapped them off, which almost always happens, which may also require re-threading/heli-coil depending on how much damage is incurred and if you dropped the ceramic into the engine (that's even more fun to deal with!)
I think book time is 3hrs to do spark plugs on a 5.4L V8, which assumes you're cracking the sparkplugs open an 1/8"-1/4" of a turn, using Carb Cleaner (no more than I think a teaspoon the TSB says) and letting it sit for about 20mins before you do anything to that spark plug.
Look Ford has some nice trucks; I loved my Dad's '05 F150 4WD FX4 with the Triton V8 and fully packaged it was a fun truck. But that doesn't change the fact that you're telling a customer "its 3 hours to change spark plugs, even though it looks like its a 30 min job, oh and chances are you're gonna be waiting longer when we break one or more spark plugs in the engine."
It was as a bad a design as them putting only 3-4 threads in their older V8's cylinderhead for the plugs. They flipped and went with these ridiculously long plugs that build up carbon because they market them as "long life plugs" and so no one touches them until their 100k, with carbon built up around the inner shaft so they snap off instead of come out normally. You're right, once you actually get the plugs out and put good quality ones in with a little anti-seize on the plug where the TSB tells you to help prevent carbon deposits forming its great! But the point is you still need to get the first plugs out before you can do that and I know a handful of techs who have had far more experience than I have had in my life who do everything right and be patient and still have them break and once or twice have to rebuild the heads for the customer as a result. Its a 20+ page TSB for christ's sake! :O Most people who buy their used Fords are going to have to get the plugs done because of being under 100k so the plugs never got changed, because the previous owner was lazy and didn't change them, and/or they got sticker shock when the dealer quoted them 3hrs labor, plus over-inflated parts cost for their Ford plugs, and the disclaimer of potential engine damage doing the plugs.
And for those of you who have no idea what I am talking about: