Tiresome argument, the idea of having high capacity players is so when you think of something that you want to watch or listen to, it is available to you at that very moment instead of having to hope it sync'd this time around.
Besides file sizes are getting larger not smaller. Digital collections get larger over time, not smaller.
Before someone throws up the cloud argument...Local storage is vastly superior to cloud storage in speed, reliability (no server down times, crashes, poor connection reception), cost (one flat fee instead of monthly) and security (you own your files instead of having a company, who's bottom line is money not your data).
64GB capacity was available when iTunes was still 128kbps, there were no high definition videos or retina displays that made app sizes double. Flash costs have crashed, Apple is simply milking the cow with capacity price points right now, 128GB is definitely equal in cost now to that of the 64GB then.
The fact they added cost to the 128GB iPad is completely ridiculous, its definitely not costing the company anywhere near the $100 price difference..in fact it probably costs the same as the 64GB model.