You got it, Migraine (wait, is that a double entendre?).
Having so many keys hard-coded means that if you re-bind them *outside* the game, you will not be able to perform the function assigned to that key (unless you assign the original key to another key - but that only works if there are no conflicts).
By conflicts there I mean if the game wants the arrow keys to be used in conversations and you remap them to WASD, and say to remap ESDF to the arrow keys for conversations, you need to remap something else to E... and I'm not even sure that world work, depending on how the flash menus work (the menus in the game, at least most of them, are SWF files, or Flash files).
E, Tab, and the Arrow keys are hardcoded, and the numpad is reserved (and I'm not sure but I think they're not coded into the menus). There may be other keys as well, probably anything else used in the Flash menus, like the TCS(?) keys in the face menu.
I'm seeing complaints about the keys in the construction menu, it looks like maybe the WASD and arrow keys may be hardcoded there as well.
I really need to play something else.
edit: ESO now has a launcher error. (bangs head on desk)