I was trying to be all subtle and indirect and sh*t in my prior post, but screw that. Yeah, when you said "first step" of IP, seems Lee and I interpreted that to mean it's one of the IP skills. You've clarified you didn't mean that, which is fine, but since at least two of us read it the same way a clarification was in order.
As for others, I don't know what background they have (hint: it's not all the same) so I don't know what's confusing and what's not. Good structure is all very well and good to work on but you don't need anything special to work on it--yoga, taiji, or Alexander Technique will all do just fine. As far as I'm concerned, what Lee's talking about is the alpha and the omega of IP/aiki--that is, until you've started on it you haven't started your journey, and you'll be working on it as long as you're pursuing aiki at all. So talking about structure and alignment is misleading in its own way--almost anybody can read it and say, "Oh yeah, I work on that too--what's the big deal?" Whereas pulling silk/six directions/roppo kamae is the heart of the matter.
(Well, almost. Really, in my current understanding, in-yo ho is the heart of the matter. But you can't get there without six-directions.)
And how much time did we spend learning any structure with Dan in the beginning? Almost zero. Unless you were a complete and utter mess, he basically never said much about it. What did he start us on immediately? Pulling silk/six directions. What will we probably be working on forever? That.
I had a previous background in training the idea of structure from yiquan. It did zip for me, nada, with regards to this material. I had to dump it on the cutting room floor. It was a sacred cow for me, but I had to slaughter it. So that is part of why I don't like the implication that structure is a starting point or somehow prepatory material for this. IME, it's not.