[PeterisP]

Performance and efficiency. Just as many problems need a way to store a matrix of unboxed integers or floats, many problems need a way to treat strings, possibly very large strings in a way that doesn't include any language overhead/metadata for each separate character, and allows fast random indexing, which lists don't.

List of characters works fine for the string 'Hello, world!'. It doesn't work fine for the string representing, for example, a whole webpage that you're returning, of for the string that you need to pass to some external code e.g. a regex engine implemented in C (which requires to transform it to a memory-contiguous array of chars, and then transform the results back), or for a 100 megabyte plaintext/xml/json/csv/whatever file you're processing.

[amelius]

The challenge for language designers is to abstract away the details of representation, but still present a uniform interface. (In this case, the designers have failed.)