Mostly for stability-more contact with the ground. We only set up extended stay when off loaded or I dont trust the ground squirrels ceiling.

We use some very old Reese aluminum stands (not the camcos-too short for ours) and few pieces of wood for base & top, with a full 2x4 across the front. Just snugged up, used in conjunction with the jacks, offers a lot more support. They do make camper rock steady. But generally just the simple home made copies of Torklift wobble stoppers made a world of difference. Which I had set both up at same time. Had I known how much the jack stabilizers would stop the 'wiggle' I probably wouldn't have messed with the stands, but glad I had when camped in moab sand and the wind picked up to the point I couldnt load.
The T/L is an option, Id still want to see a larger foot print on ground. That McCoy is also a really nice looking bracket, again depending where you camp is foot print..I would add some kind of spreader.
Only thing I would add is they supplement the jacks, most of the load is still on them.