I strongly believe that if you have a table, and they all have agreed to play an AP, then expect quite a bit of railroading (and I use that with positive connotations). Every single one I have read is a story, complete with exposition, inciting incident, rising action, climax and resolution. If a group expects something different, don't play an AP.
1) Motivation for the characters (and their players) to go on the adventure.
I am a bit torn with this. Rhime did these creatively; however, they were just an impetus, and there were no character arcs built around these. I think if this is what you want, then you have the characters build them. Once they build them, you have to do all the work of tying it into the story. If a player has a revenge motive, then it is up to you to pull those components into various episodic events that are already part of the adventure.
2) A story/plot/background that the GM can convey to the players - and the logical means of sharing that information naturally within the adventure.
I think this is something that could be improved upon for the published APs. But I also believe there should be expected railroading. The two go hand in hand. After each section a nice summary the DM can read to players. Yes, a wall of text complete with a few graphic illustrations. If you wanted to be creative, give each section to a player, and have them recap it in their own words. But a synopsis for each chapter would help.
When running Skull & Shackles, I would do this. I would have the maps and all the minis used laid out on the table, and then go through each one on order. It helped immensely.
3) Clear goals, which are more or less achievable (by sword, spell, or wits) by the character level range indicated by the adventure.
I agree - clear goals. Of course, there is an implied alignment with clear goals. So again, the table has to accept this. The spell, sword or wits is completely up to the players' creativity, and the DMs acceptance level of them using possible alternative methods. On a personal note, I have always found it a bit frustrating when the players do something creative, and the DM thwarts it. I find it frustrating, especially if it counters the logic the lore has built.
4) A unified theme building up to a satisfying climactic resolution
IMHO, all the ones I have played, ran or read do this pretty well.
5) Consistency and logical story/world building.
I think the authors of the APs I have seen do a good job with this. That said, it really does boil down to personal preference. I mean, if you don't want cantina (again, using this with positive connotations), don't run D&D or PF. Build your own world. If you don't want extra-planar, cosmic lore complete with Greek mythos gods and monsters, don't run D&D or PF.
6) A compelling villain, antagonist ("conflict" to use a literary term)
This is a really good one that could be improved upon. I always equate it to the Batman versus WW villains. I mean, you want depth of villainhood like Batman. Complex characters that still ring true evil in action. Characters with motive and spite. Not, some villain that just happened to be in the story's past and is now seeking power or vengeance.
Overall, a great list.
