One bitcoin on the block chain must equal one bitcoin in the formal standards world or else processing errors would be potentially catastrophic.
I agree with this. People already use XBT to mean Bitcoin (because they rightly thought BTC was not a standard name). If you tell them to change the definition to XBT = 1 microbitcoin, then confusion will inevitably arise.
The fact that current accounting software can't handle more that 2 decimal places means that this software must adapt to our needs (and use µXBT in the meantime, if it's much trouble).
People should not adapt to the software. That's not how it works.