Why are fixed length arrays passed by value while variable are passed by reference?

[ixid]

I know this will not be changed, I just want to understand why it 
is as it is.

My naive thought is that consistency is the best scheme and that 
everything should have been passed by value or everything by 
reference unless the user specifies otherwise.

I have read a comment by Andrei that they tried making fixed 
length arrays into reference types but it did not work well. Did 
the current situation arise through the reality of language 
development or is there a reason for the inconsistency?