The Tower of Druaga -the Aegis of URUK-

[xtallography]

I'd agree that would be cool... but the only people with the items to bring down the guardian shield are currently in the tower above them.

I guess ultimately it is an unknown what killing the guardian does since no one has done it before now (exception being King Gil). I guess that's an easy out for the writers to make up whatever they want and just say that it's now that way because the guardian is dead.

But the stairs leading to T2 did disappear with neeba and kaaya on them and it seemed the only way to unlock the stairs was with the rod dropped after killing the guardian. Meh, it's all speculation that will be long forgotten in a years time.