Fax is a bit modern..
The Daily Nav Warning Summary used to come through by Telex (AFTN) each night around 1800. In many FBU's the data was then plotted on the Danger Area chart in chinagraph. Pilots could see at a glance what was relevant or not..
Given that the format hasn't changed in almost 40 years I agree it could do with updating. There are probably FBU's that still plot this data manually whilst others will leave the info on a clip for pilots to read.
There is no technological reason why this data cannot be available in graphic format these days. Lack of forward vision or resources is much more the likely cause..
JB