In my professional opinion it is up to the RV owner to decide if they think that doing the absolute minimum possible maintenance and to use the absolute minimum "safety" margin when selecting tires, is preferable to using technology that is 30 years more advanced than some Federal Regulation or 50 years ahead of some industry standard.
Industry standards dictated by RV company lobbyists is what the current standards represent. IMO the lobbyists are more interested in lower costs to the RV company than better and more reliable products being delivered to the end user. If you feel the performance of ST type tires is satisfactory then by all means stay with those old standards. After all I ma sure that there are some folks who can get 6 years life from their tires, so for them the "minimums" worked.
If however you want fewer problems and fewer or no failures on the road and more than a couple years tire life, then you might consider using the latest and best information and technological advances available to you along with informed decision making tailored for your specific RV and usage.
In general Engineers work to make stuff better. It's because of the use of engineering principles of striving for continuous improvement we are driving cars rather than using horse and buggy. After all horse and buggy were just fine for many centuries. Even the reliable low cost Model T has been replaced because of continuous improvement being the goal for engineers in the automotive field.
Even aircraft have evolved. The venerable DC-3
met the regulations of the 1930's but I doubt that anyone would consider them anywhere as reliable or safe as a 707 or any of today's line-up of commercial airliners if traveling across the US.