@armystic, the Photon uses the BCM9WCDUSI09 (P0) module and adds other components in a nice through-hole or surface moutable (castelated edges) package which is perfect for makers and developers. Key here is the addition of the onboard antenna, LED, buttons, regulator, and FCC certification. The “bare” P0 is the module which you described above (wifi + STM32) and it is available separately for volume production. Adding your own antenna, etc. will mean that you must get FCC certification.
The BCM9WCDUSI14 (P1) module combines the BCM9WCDUSI09 and a PCB antenna/antenna connector in a single shielded package which is also FCC certified (though not wearable certified). The module still requires regulated power and external decoupling.
Several members hand-built Cores and Photons successfully. Buying the modules from Particle means that factory Particle firmware is already installed and the one-time cloud access license ($2/device) is covered. 