Re: it's already bad enough with dbus...
Well then, you're not the typical user. The typical user expects to be able to access the card from the moment they stick it in. Perhaps the image writer should be smart enough to realize this ahead of time and request a dismount of the card before writing to it.
Even Microsoft's excuse for an OS will pop up a dialog box telling you it can't read the disk (ok well IIRC it tells asks you if you would like to format it or something silly) or doesn't understand its filesystem. I have had that happen when accidentally inserting wrong flash drive and the popup saved overwriting a portable BSD boot drive that I had not remembered to label as such.
I really really do not want systems trying to be clever and doing stuff behind my back thinking they know better.