It doesn’t matter where you draw the line of long distance, that is obviously arbitrary. What matters, is to involve as many riders as possible in the awards system.
It’s about inclusion, BR are not necessarily for all. The more prestigious awards will always include long and possibly overnight brevets, but the points system should apply to all brevets. The shortest brevet is a 50, hence half a point is appropriate.
If a 50 is validated, then it means it is an Audax and therefore by definition it is long distance cycling, whether you like it or not.