Only without fast travel can you get that much gameplay. And its not really gameplay, its walking.
Actually, exploration is a big part of Skyrim's gameplay. So you basically just chose to ignore content.
No it's not. You're trying to compare an apple to a banana. The concept of fast travel does not exist in ME3. That is, I thought travelling from planet to planet was handled similar to ME2. If it's similar to ME1's system of simply selecting a planet and appearing then, then it does actually exist.
Now, you're focussing on the wrong thing. By your particular breed of logic displayed in this tread if Bethesda had shipped an extra two DVD's filled with nothing a "01" repeated over and over again we'd have weeks worth of gameplay time extra.
You want
content, not just more space on your hard drive. Or to put or more simple: it's not the size that matters, it's what you do with it.