Motivation for New
There are many computer languages out there and takes a lifetime to learn them all. The languages with the strongest position in software industry are: Fortran, C, C++, Onjective-C and Lisp. New computer languages are created because old computer languages can not be fixed.
Once a computer language was used in production it is needed unchanged for support. If is changing too much then it becomes a new computer language. This is what happen to Niklaus Wirth languages. They have evolved too fast: Pascal, Modula, Oberon. All genial, all forgotten.
For developers is very difficult to switch from one computer language to another. Every new computer language promises to correct previous issues from other languages. Some languages may have new paradigms that may be even harder to grasp.
Sooner or later programming languages will be ruled by politicians. We will have regulations surrounding programming activity and probable the government will approve one or other language for critical applications.
On the contrary, programmers will refuse to be regulated. We will have rogue programmers leaving in anonymity and doing amazing new languages. These languages will be so influential that government regulated languages will have no choice but to copy us.