In my opinion those weapon proficiencies are good enough. Sure, they might be not useful for every character, but there are enough combinations that benefit from it.
The most obvious one is elf rogues being able to use Gontr Mael.
Other good options that come to mind are the Dwarven Thrower on a dwarf monk or the Silver Sword on a gith cleric or bard.
There are also some pretty powerful medium armour options like Sarevoks helmet on a dwarf rogue or the Dark Justiciar half plate and helmet on a dwarf warlock.
