Yeah not enforcing the meta doesn't mean they'll forgo balance/design decisions, just that you won't get in trouble for building kog as an AP off-tank in top lane.
AP kog can/could be a little too safe while putting out rather a lot of damage, so it's not really something they want from a design perspective.
A late game hyper carry glass canon who can carry a teamfight if protected is what they're going for, but that's a tough balance thing to reach. The 5 AS kog overshot the carry thing to the point where protection wasn't needed. Current kog isn't necessarily 'that' bad, but is somewhat outclassed by alternatives.
I'm rpetty sure they've acknowledge that he needs more work, but they can't spend all their time reworking kog and then reworking ryze and then reworking kog...