[[:Category:en:Area codes]]
Fragment of a discussion from User talk:Rua
I disagree. And I stand by my comment that if you are going to remove the categories, you should then immediately add them to the data module. Otherwise, you're just pedantically orphaning a category.
Manually adding categories is a useful stopgap for (the vast majority of) people who don't mess with data modules. And, IMO, it's ridiculous to base categorization on something that few people other than you can understand.