Was talking about this in another thread, but I do think it's pretty clear why the ride has moved away from car safety testing to what it's been in 2.0 and now 3.0.
Cars are not advertised with promoting their safety record anymore. Back when TT opened, this was a big method of advertising and you saw a lot of these test videos in car commercials. But that's just now how it is now. Cars today are sold based on their aesthetics, their amenities, and their technology.
GM has the opportunity to advertise to millions of people in the busiest vacation destination in the world. They are we all aware of what captures the public's attention about cars these days and it's whatever the shiny new tech is. People don't really think about or ask about a car's safety anymore. People take it as a given.
So what does that leave you with?
The company's innovative tech being the focus of the attraction rather than its safety, or how that safety is tested. People seem to forget that this ride's primary function in GM's eyes is to be an advertisement. Disney gets some freedom in how they go about doing this, but they are still being paid by GM to build an attraction that advertises what GM wants them to advertise and presents GM's cars in the way GM wants them to be presented.
GM doesn't want to talk about safety or testing anymore. They want to talk about them being a cutting edge company incorporating futuristic technology and innovative ideas into their product.