Why do not all Syntax elements have a SrcLoc?

Is there a particular reason why only "top level" AST elements in the Language.Haskell.Syntax libarary have a SrcLoc attribute? It would be very handy for my application to be able to know the src location of each AST element and I was wondering if there was a deeper reason why that's not the case. Also I wonder if other would be interested in an extension that captured the start (line,column) as well as the end (line column) of AST elements (handy for rendering src). - Reto