Q u o t e: That's my belief too.
Hydra represented Starcraft.
Titan is in line of the same naming convention.
2nd reason: It is a horrible name to be used.
Doesn't match Blizzard's creativity.
When people picture Titan, they picture a bazillion other things that had the same name.
Actually, Project Hydra was the code name for Diablo 3. What of the early concept arts on the site is a screenplay of a cinematic with the title of "project hydra" on it. Here http://us.blizzard.com/diablo3/_images/artwork/ss38-hires.jpg