this is an interesting topic b/c of the nature of the heain/pinan kata.
it is accepted itosu anko created these 5 kata. they are simpler and more basic and were intended for beginners and children and for introduction into the educational system. as such, alot of the sequences don't make perfect sense or seem dissconnected. its also said alot of the techniques were made less dangerous.
to understand the pinan/heains you have to understand were thay came from. were they totally original creations by itosu? probably not. some jka types feel they are related to kanku dai/kushanku. another theory is they were created out of an older, more sophisticated kata that has since been "forgotten." this would be the channan dai/sho kata.
i recently acquired an analysis/application book of these kata and it is very enlightening, particularly with regard to heain/pinan application. it is "channan: heart of the heains" by elmar schmeisser. i highly recommend it. the channan kata themselves are fascinating. see my post in this forum about it.