The iPhone Air is a weird phone but that's mainly because it's a test device in production.

Everything on the Air is something Apple wanted to test ahead of the foldable iPhone. The weird big battery, the single speaker, the mainboard under the bump, and all of the custom silicon they threw at it (from the modem to the WiFi chipsets).

Same reason the 16e existed, not to sell a cheap iPhone, but to test the C1 modem in production as a "finally ready to ship in beta" product they didn't slap the beta label on.