So much material here, I don't know where to start.
I never liked the idea of two foot driving (probably because I never had an autotrans until I had gotten addicted to using the right foot for both brake and gas.) The very WORST issue surrounding two foot driving has already been mentioned. There is a natural tendency to depress the brake pedal sufficiently to illuminate the brake lights - even though no braking is taking place. I read a book called "TRAFFIC" which had a whole section on why (otherwise) normal, smooth-flowing freeway traffic becomes snarled. The worst offender - two foot drivers (distant second were those who go for the brake for every curve, sign, exit, entrance, dip, bump, etc.) It turns out that traffic on freeways can be affected for miles by ONE driver illuminating his brake lights - even if he slows down not at all. The MYTHBUSTERS confirmed this not so long ago. So there's that.
A little practical advice: If one has become used to applying the brake and gas to hold on a hill, it's time to learn about using the hand brake instead. That's how we learned to do it in drivers ed. I've never forgotten it. Of course, GM and others still use the foot emergency brake which is a bit more challenging, but it still works - also the way we learned it in drivers ed when all cars were GM or Ford in drivers ed.
On a less serious tone (though it was serious at the time) I will relay a story of the battle of the sexes (back before THEY won it.
) DW and I were at a dinner party with several couples. The conversation took off on how irritating it was to ride with our wives. There were several "issues" discussed. MY particular pet peeve was my wife's tendency to accelerate until she was forced to stop. IOW On the gas until a crash would occur without vigorous braking. Personally, I've always tried to "play" the traffic, watch the lights ahead, etc. With DW, it's either go or stop. So I said "All women must have learned to drive in a Kiddy Kar. They don't think they are driving unless they are pushing a pedal." My statement (admittedly under a little "influence of wine") got a big round of laughter - from the men. The ladies, especially DW were not pleased. So, I did my best in the future not to criticize DW's driving, though I can't always resist showing her that I get 25mpg and she gets 22 on the same car with similar trips - guess it's just a guy thing. In all things related to the sexes, refer back to rule #1. "If Momma ain't happy, nobody's happy."
Comment on a fix for a nonexistent problem: The disabling of the gas pedal upon pushing the brake probably has already been discussed as a response to folks accelerating through their garages or running into crowds of people because of a "demon car" which could not be stopped. IIRC most if not all incidents have been shown to be those who think they are pushing on the brake but are actually pushing on the gas. In any case, the most powerful car ever built can be stopped - even at full throttle - with normally functioning brakes. Naturally (in all of this) YMMV