small thing, that crystal was never stated as hydolyn or as zodiarc, so we cannot say which one of the two it is, also zodiarc's full title is Zodiarc Keeper of the parceps aka keeper of law, the asceans are willing to cause chaos to summon zodiarc, but why would a being of chaos be summoned by chaos, unless he wanted to make it order,
also one thing the game has done is never state which side we are fighting on, we are called the warriors of LIGHT yes, but in some final fantasy games the warriors of DARKNESS are also the good guys, :P SE' loves this grey area also the link name in your file was "darkhydaelyn" so that also points to the uncertainty of this,
i have my own theory that we are causing more destruction under hydolyn and the ascent want to correct all that has been done.
(also do not say we are good because of the characters saying so, the characters saying that are also granted the echo or we are helping there own cause, besides the good batsman of eorzea that word is easily doubted in the long term.)
EDIT
to go along with my theory, which states that hydolyn is actually bad, i image the fact that we have been killing the primal just for them to be resumed taking a lot of aether causes a lot of harm to hydolyn, that or, we are not doing what we are meant to do, the ONLY time she has actively helped us was against ultima a ALLAG weapon capable of CAPTUING the primals, meaning she could of been helping up only to FREE the primal and not due to saving the 5 races, you also have to think with the power she wields why hasn't she got any beast race followers and she insists on tempering the 5 (now 6) races.unless we were lost of the path she wanted us to walk,
though this is all a slight fan theory, but i beleave that hydolyn is actually the dark crystal (pictured above) and the caissons are trying to find a way on purging the world of it, using zodiarc (which could of been the 6 races original primal) aka the one true god of eorzea i point most of this onto elebus and the other asceans they seem to be calm and trying to talk there way and explaining themselves lahabria is more of a extremist compared to the other 13 members so far
also yes i know i was late to this thread it grew FAST o...o