I think it would be useful to think about the purpose of adding if-then
statements.  I don't particularly like nested if-then-else statements,
because it may be hard to follow the logic behind the conditions
sometimes.  I have seen extremely messy C-code or LISP or PROLOG code
for that matter, so elegance is not really in the kind of language you
use but how you use it.  Reading pages and pages of code is never fun
and in the case of Csound it is a textual representation of something
that should be represented as a diagram.  That is why I think something
like Visual Orchestra is useful.  If we need more elaborate ways to
control the flow of things we should think about a method to represent
that graphically rather then burdening the language with additional
constructs.