Non-requestive inshāʾ is not pointless speech. It simply does not fall under the definition of requesting a not-yet-realized object or action. Oaths, exclamations, praise and blame, and certain contractual expressions perform distinct communicative or operative functions.
وَاللَّهِ
By Allah!
This begins an oath; it does not direct someone to perform an action.
نِعْمَ الرَّجُلُ زَيْدٌ
What an excellent man Zayd is!
It expresses praise. Such a formula is not a request for a future action. Not all speech that is “not khabar” should therefore be classified as a command.