string and char[] in Phobos

[Puming via Digitalmars-d-learn]

Hi,

I saw from the forum that functions with string like arguments 
better use `in char[]` instead of `string` type, because then it 
can accept both string and char[] types.

But recently when actually using D, I found that many phobos 
functions/constructors use `string`, while many returns `char[]`, 
causing me to do a lot of conv.to!string. And many times I have 
to fight with the excessive template error messages.

Is there a reason to use `string` instead of `in char[]` in 
function arguments? Do you tend to change those phobos functions?