This is one of the greatest periods in history for performance motoring. You can have more horsepower than anyone could fathom in 65, and drive it every day for 200k miles. I guess if you wanted to put plywood on the roof of your hellcat, you could. Or you could buy the upcoming hellcat grand Cherokee.
I see your point, but Buick Avista is truly another version of a well-explored recipe: the two seater sports car. While it claims to be a 2 + 2 seating, only small children could actually be seated in the back and trying to put a child safety seat in the back of that car would be a serious challenge. So in the end, Buick is pulling a fast one in calling this car a 4-seater and buyers will soon realize that.
At the same time, what made the American muscle car great was it versatility. It could seat 4 adults and had a standard sized trunk. It was a car a man could drag race and still take the family out for a vacation. The Avista is at best a commuter and fun car. These days it is common for both parents to have their own car, but it is also common that each car has to be able to deal with that parental chores - the Avista is poorly suited for that role. So the potential market is limited.
At the same time demographics have changed. During the muscle car area, women weren't driving enthusiasts, that's not true anymore. In our neighborhood, German and Japanese wagons are increasingly popular. Few people actually need off-road capability and lets face it, a "high-performance" SUV looks like a pregnant guppy on platform shoes!

There is a market for high-performance cars that can take the family places. Detroit isn't taking on the imports for that market.
I'm personally disappointed that Detroit cannot seem to reinvent the American muscle car in a way that public approves of. The closest thing that I can think of to 1960-70s muscle cars is last generation Dodge Magnum. Judging from what happened to the Magnum, it appears the American public has lost interest in the tradition of the American muscle car. That seems like a very sad thing indeed.
Edouard