So, from the executive summary, it appears that NASA looked at the throttle system and was unable to find a systematic explanation for it being stuck open. A stuck throttle, by itself, is quite awkward but if you have a working brake override system, an awkward lurch will be as bad as it gets.

But regardless of what NASA did or did not find, there were real accidents involving throttles which were stuck open for minutes at a time with the engine completely overpowering the brakes. Recall that in the 100mph LA crash which set off the investigation the brakes were completely destroyed.

That is a real design flaw, an error of commission by Toyota. Other cars, for example VWs, have a brake override and the drivers manual documents an accelerator "double-tap" protocol for giving the accelerator priority, say when starting on a steep hill.

Furthermore, in the week after the recall, the president of Toyota announced that Toyota throttle systems would henceforth include a brake override. Here's their official press release making good on that promise:

http://pressroom.toyota.com/pr/tms/toyota-extends-brake-over...

So I can't develop too much sympathy for Toyota. They made a basic design mistake in a safety critical system, and then refused to acknowledge the problem. That mistake and their mishandling of it cost them a ton of money and that is exactly as it should be.