Li Shenron
Legend
Anyway, I think that your concern may be in the fact that these proficiencies cost a feat, and feat are few and valuable so they should be taken only if worth.
I'm sure that the reason why weapon prof's were made so that 1 feat = 1 weapon, was because they didn't want non-martial classes to be "just 1 feat away" from the full-martial prof of the martial classes, and then EWP could simply not be cheaper than MWP.
Weapon groups help a lot, because they make it more like 1 feat = 3-5 weapons, so it starts feeling more worth for the feat cost.
I'm sure that the reason why weapon prof's were made so that 1 feat = 1 weapon, was because they didn't want non-martial classes to be "just 1 feat away" from the full-martial prof of the martial classes, and then EWP could simply not be cheaper than MWP.
Weapon groups help a lot, because they make it more like 1 feat = 3-5 weapons, so it starts feeling more worth for the feat cost.