You don't travel much do you? I don't either compared to some, but I do it enough to understand why streaming isn't an option. Every airport I've been to has both terrible WiFi speeds and 3G speeds on AT&T. The networks are just overwhelmed by the number of people trying to access them. Hotel WiFi is also usually hit or miss. Not to mention the fact that streaming does you no good while up in the air.
As for your question about consuming all 55GB between syncs, get real. I also doubt many people actually do that as well. But that's not the point. Even before the days of streaming, do you really think people would consume all 80GB or 120GB of content on their iPods? But they still wanted that much storage. I don't know what I'll be in the mood for later today, let alone a week from now, which is the typical length of the trips I take. So I need a wide variety of content available to me while I'm away.
All of this was illustrated during Thanksgiving week. I took a road trip from Houston to Colorado. You're not going to be able to stream content while driving through some rinky-dink town in the Texas panhandle with a population of around 200.
I'm not sure anyone is saying that a huge market is being alienated. But it is frustrating that the iPad 4 has the same storage limits as the first gen iPad. I also find it a little maddening that when Apple added 64GB to the iPhone, that they charged $100 more for it. I thought memory prices have been going down for years now. So why are we stuck with the same capacities at the same price points that we've had since the iPhone 3GS?
I have the same concerns, you are absolutely right.
It seems that we are not the average user.