Beardy spell use that went through 1e and survived through to 2e because no one had tried and/or questioned it.
Wizards Eye is easiest to explain as if you think of the Eye as a sticker, everything in front of the sticker can be seen, behind can't. Someone pointed out that RAW you can cast it onto the floor (or low-terrain) such as a sewer cover and give yourself 360 field of view.
Joe has said the intent of the spell (from 1e onwards) that was that it was cast on vertical surfaces. It might be errata'd, but he has said he doesn't like to change RAW via erratas unless it's really bad for the game.
So I suggest we go with intention for the spell use? (I don't have it, for disclosure.)