Genuine question, why do you assume it is a restriction? I am a professional developer and not a researcher or scientist which is the original target for Julia. Yet I find Julia to be my favorite language, and I've tried a lot of them. I can't think of any language which I find as expressive as Julia apart from Haskell, but that is exceedingly cumbersome to deal with given the strict type system. Haskell is beautiful but it is overly academic and requires a lot of investment in time and brainpower to work in your favor. Julia on the other hand is quite quick to learn and gets you productive quickly.
I'll mention multiple areas I think Julia excels. If you want to write quickly high performance numerical software then I don't see what the alternatives are.
It is the best language I've encountered for writing shell scripts. Bash is terrible due to the difficulty of factoring the code into functions and the frequency in which you forget to quote variables properly. Many end up thus using Python or Ruby. Ruby seems very popular, but Julia really works better. It has tighter integration with the shell and handles chaining, reading and writing to shell commands much nicer.
It also has all sorts of useful stuff ready to use out of the box and sane function names etc. I find it much more cumbersome to write shell scripts with python. Awkward to call processes. Got to always remember what every little module you got to import. Because of multiple dispatch, Julia allows much better naming of functions.
And as a computer language geek I love powerful LISP macros, but I can't get used to LISP syntax. Julia is the only language I know of which gives access to powerful macros and code generation similar to LISP.