Perhaps because the tools that we have already are already good enough.
"Why don't we have any new programming languages" or "Why don't we have any new web frameworks" or "Why don't we have any new operating systems" or "Why don't we have any new container orchestrators" might be the same kinds of questions as "why is the design for washing machines still basically the same as it was 50 years ago?" or "why are we still using English, where are all the new conlangs to replace it?" "why are we still using email/SMTP instead of inventing a better system" "why haven't we invented a new calendar?"
You're saying there's nothing left to invent. I think that explains a lot of the complacency around considering AI to be the last ever frontier for progress. I obviously don't agree. I've gone looking into "why don't we have better version control" and the answer is definitely not that we already have all we could want.
"Why don't we have any new programming languages" or "Why don't we have any new web frameworks" or "Why don't we have any new operating systems" or "Why don't we have any new container orchestrators" might be the same kinds of questions as "why is the design for washing machines still basically the same as it was 50 years ago?" or "why are we still using English, where are all the new conlangs to replace it?" "why are we still using email/SMTP instead of inventing a better system" "why haven't we invented a new calendar?"