TallIan
Explorer
As other have said, it was done this way in older editions and it doesn't really add much to the game. As a fighter, I rarely used anything other than an ax is I was a dwarf or a sword if I was a human.
So you end up with two choices;
1) Give martial classes enough weapon proficiencies at first level so that they are more martial than other classes but can use all the weapons they want to anyway (sword and bow; ax and crossbow; two swords; etc.) this just means that proficiencies gained later are meaningless
or 2) Give martial classes one proficiency so that they have to learn more later on to become more versatile - or even to realise their concept. Then what do you do with non martial, non caster classes like rogue? With a weapon proficiency, they are as good as a fighter and without a weapon proficiency they are rubbish.
This is one of those idea's IMO that sounds cool but is really just extra bookkeeping.
So you end up with two choices;
1) Give martial classes enough weapon proficiencies at first level so that they are more martial than other classes but can use all the weapons they want to anyway (sword and bow; ax and crossbow; two swords; etc.) this just means that proficiencies gained later are meaningless
or 2) Give martial classes one proficiency so that they have to learn more later on to become more versatile - or even to realise their concept. Then what do you do with non martial, non caster classes like rogue? With a weapon proficiency, they are as good as a fighter and without a weapon proficiency they are rubbish.
This is one of those idea's IMO that sounds cool but is really just extra bookkeeping.