That the C172 is still available 60 years on means that modern tech ain't as great as people think. There plenty of newer ideas that have come and gone in the meantime.
That's not saying it can't be significantly better. Just that not enough people are prepared to pay for what it takes to develop it. Whether that's regulatory strangulation or the collective failure of the market's imagination is debatable. There's little reason why private flying couldn't be a much larger part of our lifestyle though, but plenty of reasons why it isn't.