FWIW, I did propose that the TR requirement be dropped because of the difficulty this presents to someone testing a receptacle with their meter probes.
The committee did not consider that to be an issue, and rejected the proposal.
As for the "WR" requirement, one might, just maybe, argue that there has always been a requirement that devices be appropriate for their environment, and more corrosion-resistant devices have been available for some time. There have been industry-standard exposure tests for at least 50 years.
Of course, things are never that simple. The first question is: how good is good enough? Do we want the device to last 100 years or 1? I've replaced falling-apart economy devices that had managed to hold together for 25 years; I can't really fault the device after all that time. So deciding where the $20 devices were to be used has been a judgement call, usually reserved for industrial settings. The code change removes some of the discretion from the matter. To be fair, the devices are now (amazingly) available for a much more reasonable price.
The other matter is: How can you tell a corrosion-resistant device from an ordinary one? Well, that's what the marking is for.
Is "WR" the same as what was marketed as 'corrosion resistant?" I don't know; it's possible that there is a less demanding test. It should also be noted that the $20 devices were only a bit more expensive than the 'non rated' spec-grade devices they were based upon. The new "WR" devices are most certainly not spec-grade! Indeed, the industrial devices are NOT marked, and would not meet the code requirement - regardless that they are certainly up to the task.
Going back to the "TR" devices, the same issue applies. All previous tamper-resistant devices are meaningless without that "TR" marking. It matters not that you can actually see the protective mechanism.
Manufacturer driven? Inspector driven? More critical to me is that these requirements are another example of the code changing path. No longer does the code tell you WHAT you must accomplish; it tries to specify HOW the job will be done.
Such a trend really bothers me. That approach turns our entire context inside-out; the code will necessairily expand from one big book to something akin to the tax code, and (like the tax code) be chock full of confusing, contradictory requirements. Instead of order, chaos will result.
A certain road, paved with good intentions, comes to mind.
