But you haven't answered the question. Why Mathematica and not Lisp + some libraries? Or (+ Lisp Libraries). Again, there are many organizations willing to adopt any language that will give them some extra leverage. Lisp just doesn't appear. The explanation that the average programmer just isn't smart enough is easily demolished by pointing out the C++ (and APL, and Haskell) users. So either we're all missing something or the elephant in the corner is that Lisp just isn't that useful for commercially relevant problems. Which is not to say it's a bad language, but that it's not the "secret sauce" everyone's looking for.
Actually, the question you are asking is "Why mathematica and not Common Lisp or Scheme + some libraries?"
Mathematica is lisp + a bunch of a math libraries + vendor support + slightly different syntax + renamed functions. The syntactic differences:
{a b c} -> '(a b c)
f[a,b] -> (f a b)
a == b -> (Equals a b)
(* comment *) -> ;;comment
Since there is no advantage to different syntax and renamed functions, people choose mathematica over other lisps (and grumble about the weird syntax).