Thanks for the great explanation. Sounds like a great safety to have, if you have the money to fund it. Do most springs have the military wrap?
Keep in mind: I have NOT spent meaningful time off-road in my rig so this is all just knowledge gathered from my own reading and regurgitated here. I'm sure there are a lot of different opinions, hopefully someone with more "real world" experience will chime in over the benefits of military wrap - I just know I've been told to look for this as a consideration/differentiator in aftermarket springs.
OEM Toyota springs have them on one side (spring pin side, not shackle side). I know HFS and OME do as well. It probably depends on your intended use. If you're doing a lot of rock crawling, or towing heavy loads, it probably makes sense to have them. If it's more of a driver, and less of a crawler, you may not need them. It seems like there are quite a few other axle/suspension components that would snap before a leaf spring but it is good insurance!