Why kibana use match instead term when filter visualisation?
I believe a term query and a match query should behave the same when applied to a keyword field, which is the type of fields visualizations are built on.
fwiw, you can change the filter query if you wish to use term instead of match:
Is there a specific reason you would like to see term used by default instead?
No, despite the fact that you don't need to append keyword in text field. Thanks