Pitch detection is hard. Really, really, really difficult to do it correctly. You need:
- a very good input (a good microphone, a well tuned instrument)
- a good detector (the cheapest, optimised for electric guitars are starting at 200-300$)
- for piano it gets more complicated, if you want to detect chords, etc.
To do the software side correctly: it's a nightmare. To do the hardware side: it's expensive (and would skyrocket the support requests, that "this-this-and-this does not work"). I totally see, why PGS originally didn't implement this feature, and why they have shivers from it in any future iteration. I can only guess, how competitor softwares (FlowKey, Yousician) do it, and my guess is: poorly.
Hell, even with a perfectly working USB connection, if I hit a triad, and one of the keys is slightly (I measured: 20ms) off, it won't be picked up as a proper chord. Can you imagine all the magic, which has to go into a pitch to midi converter (that's the official term for the gadget, which here is discussed), hardware and software wise?
Think about this: you must play an A minor triad in first inversion (C-E-A) after a C major triad in root position (C-E-G) in the same octave. These share two keys. How do you think the pitch to midi converter can decide whether the C and E keys have been released and played again or they are just held? (Assuming good dynamics in your play, so you are not smashing the keys when you are playing the second triad
![Wink ;)](./images/smilies/icon_e_wink.gif)
P.S.: if you are looking at the major open source software for composing music (MuseScore), they don't even have a feature, where you can live-record into a blank sheet from a midi-attached piano and get everything correct (chords, rhythm, etc.). That software is made for creating scores! And it wouldn't even work as many expect with a midi-connection. What would go haywire with pitch detection added into the mix?