I don't understand any of these responses. Nowhere in the OP was there a single complaint about this fight being too difficult. Several people have come back with inane responses about how it's really easy to work around the problem outlined in the OP.

Either it's some sort of server issue, or more probably (in my opinion) simply bad design. It seems like it was just a choice by the devs to begin the animations for a particular action's effect after the cast bar ends. The result is that, for example, Weight of the land casting time ends and then Titan's animation and the explosions trigger, but the explosions don't happen until Titan throws his hands forward. It's a relatively short animation, but the effect happens at least a quarter second later than would be expected. This happens with most things though. BLMs are always casting their next spell during the animation for the previous spell, for instance.

I believe the reasoning for this is that they don't want the animation to play in the event of a last second stun, sleep, death, out of area or line of sight, etc. To me though, it seems like it would make more sense in most circumstances to begin the animation early such that the visual effect of the damaging event (in this case weight of the land's explosion) occurs simultaneously with the cast bar filling to 100%.

Please understand that this isn't to 'nerf' the Titan fight(s) or any other, but simply to sync up the visual data that players are primarily using with the numerical account of what's going on. I think it would be a worthwhile endeavor for all parts of the game simply because it would make a lot more sense.