Right, but this is just a symptom of how the platform was designed. If you want "Facebook" and "Twitter" to come with the phone, it
has to go in /system/app... and by virtue of again, Android's design, APKs are not removable from /system/app. If they were removable, bad things would be able to happen with low ability to recover without requiring a user download a 100MB file, name it specially and reboot their phone holding certain buttons down.
I have no problem with addressing this as a design flaw, but it seems beyond unreasonable to use this as a way to attack Android's openness.
The point remains, he can fork CM's repo right now, make /system/app user read/write-able and go on his marry way deleating whatever he likes.
It's like attacking Ubuntu as being not open, because Gnome-screensaver doesn't let you tweak the screensaver settings (it was among the other dozen features simply removed in the last 3+ years)