I think ikkyo's title is very important, its "real" name is ude osae although O'sensei chose to call it Ikkyo, first princple/technique and the following techniques nikyo and so on. I feel he did this since all other pins and one could argue the nage waza also are built on this foundation, this first principle. If you don't understand ikkyo how can you ever hope to understand ni/san/yon/go kyo. Budo begins and ends with Rei.
It might be said that Osae begins and ends with ikkyo.