What I've learned with 15 years in the DIY repair sphere is that (obviously to me) the codes don't tell you what's at fault, only what's not reading correctly and (to my surprise) the general public will just replace what the code says is off. A MAF code doesn't tell you if it's the sensor, the wiring, or the PCM.

While I'd certainly appreciate a simple code readout because I'm pretty knowledgeable about which are actually concerning this moment vs this year vs never, diagnosis typically takes more equipment and time. The cost and hassle of the reader is negligible in the repair. I use a Bluetooth dongle and Torque app to read all kinds of stats when diagnosing. An integrated interface would be convenient in some ways, but the portability of a phone/tablet probably has an equal amount of convenience once hard diag is needed