I really think you're overestimating Nintendo here. I remember when a lot of you guys were getting hyped on Skyward Sword's difficulty going on how we were finally going to have a hard game because "Omg enemies taking a heart damage!" I was skeptical then (and rightfully so) and I'm skeptical now. Aonuma's definition of challenging is different from mine, and I think he's underestimating our abilities again.
...Sorry, I couldn't resist. Anyway, as far as speedruns go, I admit I judge length by my own biased definition of "How long it takes to beat the main quest without using glitches or hacking". This is seperate from content, which I consider "100%ing the game". This is mainly because most players likely won't regularly 100% games if ever, so I judge the "length" based off the main quest.