I don't know for sure, but I have noticed that usually people who complain run tires much heavier than stock. Jetboy is an exception with those P-metric AT II. I had AT II on a Subaru and really loved them till 20k when they got noisy. His sounds like a quality control issue.

When I ran LTD Ko2 on my Outback it could never be perfectly balanced. That tire was 39.5lb vs 24lb for stock. There was always a vibration above 60. It was not terrible, but could not be ignored. Never an issue with multiple lighter ATs.

On the 4Runner, I won't be shocked if most people complaining have tires well north of 50lb a piece. MT tires are usually E-load only and very heavy, some push 60lb and over. The exception is 255 75 17. If you forgo that half an inch of clearance the 285 70 provides over 255 75, which makes zero difference on trail, you can get LTC Destination MT2 with a 3-ply sidewall for 47lb! That's about the only MT that catches my eye and this is the reason.

I run 47lb P-metric Wildpeaks and they are silky smooth. Re-balanced them today just due to time and heavy offroad use, but there was only a very minor vibration at high interstate speeds after some serious offroad trips.

I have no idea if there is a direct connection between using D/E on lighter vehicles and balancing issues or if it is merely a function of weight.

I may be wrong about weight as well, of course...

EDIT: the just released Destination XT is 50lb in LTE in 285 70 17. So maybe that is a tire to try if you really want that size. I am very tempted by that tire in 255 75 17, LTC, 40lb!