Its not & I personally dont think that either ( dont shoot the messenger 
)
I understand your point but to play devils advocate (sorry) - its not really a reason not to add it either. It has a use, aligns with the whole topic concept and is additive (benefits those who would use it - others can ignore it).
Am I reading your statement correctly here if i paraphrase that as ...
"I'm not keen on adding such mqtt specific semantics to a non MQTT node where a well defined wildcard option could be added for wider audience benefit"
... or am i mis-reading you Nick?
If I read you right then perhaps we should close this thread off here and start a new discussion on "wildcard entry for the switch node" in a new thread?
(please note I am personally fine with a wildcard solution instead of MQTT filter)
