Ah! That makes a lot of sense.
I do know there's at least one console game out there with access to the developer console, it was brought up in a recent thread on this topic (much to my surprise, as I'd always assumed MS and Sony didn't allow this).
Two Worlds II if I recall correctly, however that was specially adapted to disable achievements too. The issue is that Bethesda games don't save the console state. So say you used the console to add 14 Daedric Artifacts, saved, and then re-loaded, then the game wouldn't have anything to say you used the console. If you then completed a quest to get the final artifact, you'd get the achievement. Even though you technically cheated because you only got 1 legitimately.
it isn't not removed from the PC version because it's difficult, removing it would be easy, but the console is a powerful modders resource that without it, most mods become impossible, and bethesda supports modding.
that said, I think microsoft and sony are taking this achievement thing way too seriously. they also prevent cheating for achievements but do nothing to stop games like Avatar and Hannah Montanna, kind of a double standard.
Removing it isn't easy. It's a lot easier to keep it in than to have to rip it out the engine or make the key inaccessible. Sure it comes hand in hand with modding, but it is just easier to leave it in.