I think some people are not understanding the stand alone question/concern some people have.
I believe what they are saying is that they believed they had to buy the base game of AJE to then buy all the addons they wanted. The problem as they see it is some of them did not want to buy/play the age of the scenarios in AJE and had they known that they would have waited for the other releases.
I only really like Roman history during the republic and find the imperial centuries to be tedious and boring. I know the history I just don't like it. If you offered me free books about the empire I would probably pass.
So someone like me would only really want to buy the games that have the republic scenarios in them compared to later ones.
I am only stating what I believe their question is about.
Personally I will probably buy all of the games, even the ones that have scenarios I do not care about in the hope that the series takes off. So that I might see an Alexander or much more importantly for myself a Diadochi game/scenario.