The premise that old languages are pinnacles of perfection is simply not true. C, Lisp, Haskell, Smalltalk, etc. – these languages did not get everything right. What they did do is get enough things right that it is really hard to make a language that is better by enough of a margin that it is worth breaking away entirely and starting from scratch. To make it worth switching to a new langauge, that language has to really make your life much, much better. Performance, convenience, safety, expressiveness – whatever a new language gives you more of, it has to give you so much more to be worth the trouble of switching to a less mature language with a smaller, less developed community. But that's what people are trying to do with these new languages.
Consider Lisp as a potential pinnacle of perfection. Paul Graham quipped that Lisp was "discovered" by John McCarthy, rather than invented or designed – Lisp already existed in the way that mathematical truths exist. That's a cute idea, but clearly not literally true. There were still a lot of design choices – parentheses for example. Why not square or curly brackets? Why not indentation? There were also choices that are now almost universally recognized as mistakes. Dynamic scoping, for example, which was later replaced by lexical scoping in Scheme.
People who haven't tried their hand at language design generally tend not to fully appreciate how many unfortunate tradeoffs are inherent in the process. Static vs. dynamic? Both have great benefits as well as major drawbacks. That's just the first major choice – and each choice affects most of the rest of the language. A coherent language design ends up being a crystalized fractal of difficult, uncertain choices. You never know when the difficulties you're facing in one area might have been easier in some nearby fold of this vast, combinatorial design space – most of which is completely unexplored. The problem is compounded by the fact that although it may seem mathematical, language design is really a subfield of applied psychology: ideas often seem great on paper, but when you try them out, people find them incredibly awkward, unintutive, or just plain annoying.