If airspace is too busy to be left to class G procedures than it must be changed to something "up", be it E or D or C or whatever. But yes, there's a cost to that.
BTW if you Brits had decent (i.e. radar-based) FIS than you could report your position and intentions on their frequency, to the benefit of all. Because of course I agree it is a small effort to communicate one's whereabouts and intentions. At least if carrying a radio - not required in class G unless a RMZ has been set up.
And by the way, @chevvron did recommend staying clear of MATZ while stating they are class G. Or did I, stupid continental, miss some subtlety of the English language?
you can legally ignore them (but not the embedded ATZ) however it would be unwise to do so