It would be great if there was 10% cool down reduction on Tear of the Goddess. So it didn't feel like you had to only build Athene's Unholy Grail if you wanted some cool down. Would open up the options a little more.

Blue buff is the generic reason for lack of AP CDR.

Other CDR option on AP champs include:

Morrellonomicon: The AP doesn;t suck
DFG: The AP is great and has a great active
Blue Elixir: You should have it 100% once you finish 6 items anyway.

Edit: Also 4% from offense masteries and 6% from utility. I think they should both be standardized to 5% though.