I totally agree with OP.
The battle system in this game is far too simplified. I don't know what they were thinking but such systems get too boring after a while or when you get used to them.
Things such as limit break could have been made interesting but instead we find it only useable by parties and guess what only DPS should use it except for few selected encounters. Lots of new lvl 50 players in my FC never knew about limit break and usually they ask what is LB I see people asking for LB.
The reason we don't have any horizontal progress is because the battle system itself is flawed. Stats are useless unless you put them all in the one thing that your class need (except for tanks of course). As for element damage I thought they were scraped due to rushing 2.0 but when I came back from my long 1 year break for the expansion I was surprised that battle system remained as it is and only added few skills that mostly made things inconvenient rather than interesting.
