By that logic why should we have a weekly tome system if those items are just going to be part of "unlimited" tomes after two version updates.

Think of it like this. Specialization recipes are just like weekly tomes, you can't gear everything with weekly tomes in the same way you can't craft everything because of specialization. But after two patches go by the "special" recipes get downgraded for new recipes to replace those in the same way the weekly tomes become the new unlimited being replaced by a new weekly tome.