Perhaps it is my "braking habit," but in 55 years of driving everything from a 1948 Dodge fluid drive to a 2015 Fiat 500 and from an MG Midget to a White Freightliner Cabover (from which I learned to stop quickly without the load shifting), I have never experienced anything like this, the exception being the Dodge when I crossed a stream and got water in the brakes. There is of course a difference between quickly stopping (as when the light suddenly changes) and a panic stop (e.g., when a child runs into the street).
If, as suggested, the 4Runner was sensing a 'panic stop" and locked up, that would seem to violate the principle of the ABS, which is to prevent a lockup in order to avoid a skid. In one or two instances, had I been on snow or ice I would surely have done so. It's been awhile since I did any brake work and am certainly not current about developments. If there is an override feature that causes the brakes to lock up in what the car perceives as a "panic stop" owners should be made aware of that. I don't find any mention in the manual, but then there is a lot I can't find there. The service folks I spoke with at my Toyota dealer agreed with my assessment, though as I said they could not find any problem with my 4Runner.
As for the sensitivity, my wife and I had also adjusted to it. But then we were away for 8 months driving rental Fiats and Lancias to which we became accustomed. When we returned, we had to adjust again to the sensitivity. The brake-grabbing incidents made me wonder whether they were related. A friend has suggested the sensitivity is a function of the large disk brakes. My concern was also piqued by the recent spate of recalls and revelations of manufacturers not revealing defects. Might there be something we don't know?
As for the suggestion to hit the gas when the light changes, I'll pass and I hope we never meet at the same intersection. Too many times have I been nearly creamed by some fool who saw the light while it was still yellow and thought that gave him/her the right to power through even though he/she was half a block or more away. I now look before proceeding.
Thanks again for all the comments and anecdotes. Very instructive, all of them.