@FJUrbansky
EvanB covered this pretty well, but you don't play EO for its story. As for variety, as I said, charting the fun I had playing the game over time, the graph would look very serated. Yes, they do introduce cool new twists every now and then, but you're then dealing with that twist for the rest of the dungeon, i.e. a couple of hours.
They're cool twists, though. In a forest, you get warped around and need to keep track of which hall leads where (not unlike the lost woods in Ocarina of Time). In a heated dungeon, you find yourself getting rid of the source of the heat, freezing water (which you now travel on, completely changing the layout of the dungeon) and affecting the enemies. Cool stuff like that.
@Evan_B
I don't have one answer for that, it really depends on how good the game is at renewing itself and keeping my attention. But honestly I don't think any RPG has ever been served well by being 70 hours long. They can still be good, but there are undoubtedly tedious parts that could have been cut out, making the game better. I'd rather have my RPGs be 30-35 hours max, but those are rare. Suikoden, Chrono Trigger come to mind. I'm sure I'll enjoy The Last Story as well.
I think being portable helped EOIV, though. You're right, long experiences on handhelds are somewhat rare. And playing EO in small chunks works well.
@happyastoria
Yeah, we recorded earlier. We'll probably talk about that topic in 2 weeks, since the next episode is the Mega Man 3 Retroactive.