I can see no reason why a TAF cannot include a PROB 05 FG, or PROB 20 TS. Sure they can make the rules such that it is only a requirement to carry holding fuel if it is PROB 30 or PROB 40, but for goodness sake don't hold back useful information that will allow pilots to make informed decisions regarding fuel and other operational matters!
I voiced that same opinion on the ADL FG -> Mildura diversions thread and got shouted down. I want to know even if it's PROB 01. I'll make the fuel decisions, MET should just give me the info I need to know.