That will only really work for the first time you call up the hatch routine, and so long as you only use solid hatches.
As soon as you use a different hatch pattern, that will be your new 'default hatch' - it seems the behavior of Autocad is to start with ANSI31, to start with, and then just "default to last pattern" after that. Every time I call up the hatch command dialog, it defaults to the pattern I last selected with the hatch dialog.