What makes 2.x less appealing to me is the change in the siege mechanism. Atleast on classic NA siege turned into a pure PvE rush, due to the removal of defense and keeping rewards. Even on divine fortress. which turns balic before each siege elyos and asmodians are kind of chilling transformed on top of each other damage racing the Dux. Furthermore I always enjoyed Baranth dredgion more than Chantra, because it can not be rushed as easily by possessing a key.
And I think this shows the mixed experiences people were having - which is a good thing by the way. For me, I couldn't wait to get away from abyss sieges, just because I hated the whole flying content as a gladiator. With chantra, I think there were both sides to that, on the one hand I hated people rushing, often a 'weaker' team with a better pve comp being able to just win. Then on the other hand, I recall it being super easy to train another team at captain in 1.x dredgion - I think the side opening in chantra made it a bit easier to manage then.
I personally won't really care whether we start at 1.X or 2.X, as both have their pros and cons, as you sort of pointed out I think. I would likely play whatever is there on release, whether 1.7 or 1.9 etc. Patch 1.2 specifically though to me would have been a huge issue in getting people to enjoy aion classic, or actually convicing someone who hasn't played aion before to try it.