The hard drives are just hand waving to give customers a precieved difference in the value of the system. They have had very little to do with the overall PS3 stradegy except that each unit must have one and its size gives the PS3 SKU it's name. I can't imagine the cost difference between 20, 40, 60, and 80 gigs is more than a couple dollars on the grand scale.
You are right that if they had know what they know now back at launch things would/should have been different and saved the company money/trouble but .... c'est la vie.
Final* Word on Game Delays:
The game will not be any better or include more content then planned. Any commnets that say so are just PR hogwash to make you feel better for having to wait.
Delays are due to lack of proper resources, skill, or adequate planning by the developer.
Do be thankful that they have enough respect for you to delay the game and maintain its intended level of quality.
*naznatips is exempt
