Sidewall resistance to puncture and tread depth.s
I wouldn't buy them otherwise because they add a lot to the rotational mass and unsprung weight.
Some sizes are only available in a LT/E.
A few good reasons to run 10 ply on 1/2ton...a few good reasons not to as well. Depends on the purpose/use. If the rig is genuinely off road or typically pushing/exceeding max gvw its certainly warranted. If its mostly a pavement princess its just killing ride and handling for no good reason what so ever.
There is definitely something to be said for durability and puncture resistance...to a degree. Sharp/pointy stuff gets through 10 ply as well, just takes a bit more to get all the way through.
That being said I have a customer that monitors gas wells on a landfill with a few trucks. The tires on those trucks see more abuse and nasty sharp stuff than any even dedicated off road rig. They use up a set of tires about every 3-6 months, sometimes less. By use up I mean so cut up and punctured slime and 15 plugs wont even keep air in them long enough for a days work.
They run exclusively premium brand 10
ply mud or all terrain tires on compact and 1/2 ton trucks. Anything less they don't last a month up there....so I'll say the durability factor is a valid point based on experience in a very harsh environment.
On the other hand, I put 10 ply on my wifes tundra due to that being the only thing available in that particular tire/size I wanted at the time(covid era) and I can't wait to wear them out. Killed the ride and handling on that truck to the point Id take them off now that standard load tires are available in that size...but it doesnt get driven much and she doesnt complain so I'll save the $ for now.
As for tall skinnies, they might look a bit goofy from the front or back, but the functionality of higher ground clearance, narrower track width and more concentrated load distribution for off road use certainly give them a functionality edge especially on western 2 tracks and the like.