Tim
Up to a point you are right.
When I go flying I have a range of trips I can do from staying in the local area, to flying to my local £100 burger establishment to making a more distant trip to relatives.
All of these can be achieved on many UK days. I use the wx to plan a flight (and return), but have often found that the pessimistic nature of many of the forecasts lead me to under-spec the day's outing
I have also found that there are occasions where significant weather events were not forecast, but have appeared after I was in the air, and then were entered on the updates.
I am a bit of a weather 'nut' and getting irritated at the way that the forecasts just don't seem to bear any semblance to the actuals. The TAFs and METARS for the reported TAF period could be for different airfields.
I have great respect for the Met Office staff and their professionalism, but from time to time I'd like them to look out the window.