"[ ] You have reinvented PHP better, but that's still no justification"
I always like this one. Even thus I have no real thing against PHP, it makes me smile.
* C - assembly and machine languages are not portable
* PHP - the barriers to entry for server-side web programming are too hugh
* Java - C++ becomes too error-prone with large teams
* Clojure[0] - there's too much complexity in programming that isn't inherent to the problems being solved
* Ruby, Python - Perl is really useful, but a little too messy
[0] Calling Clojure popular may be pushing it, but there seems to be some momentum building behind it.
That is more or less what every language is trying to achieve. It would be more accurate to say "Clojure: All other Lisp implementations are impractical".