I see RS232 as more of a programming interface
or tool. Crestorn and AMX weren't really developed
for the home AV market originally. They were developed
for the pro industry (convention sytems, etc.)
Most people that use a Crestron system in a residential
sytsem use wireless models, and other than programming
the hardware. It's all RF and IR . In a hardwired
scenario such as a large convention centre or
a venue that has a dedicated complex hardwired
multi-zone AV system, it's totally interactive
with feedback, and yes was developed for the PC
platform well before most of the hardawere that
has followed. you will see RS232 in industrial
situations such as ice arena's where temperature
and other parameters are provided in real time
via RS232, or HVAC systems , etc.