Animation lock would be fine in a game with no latency. The major issue is the positioning/environmental damage that has already been seen in the Ifrit fight, and the devs have said such fights are only going to get harder. So, the three ways you can die to this kind of thing are:

1) Being dumb, which is a fine way to die because you need to learn how to play better and everyone gets to have a laugh.
2) Latency/lag, which is not fun.
3) Animation lock while standing in a hazardous place.

The problem is, with the way that data is handled in XIV and the fact that you can't control latency on both your side and more importantly S-E's side, when a combination of latency and animation lock hits you, there's no strategic element to it. Your move may keep you in place for 1 second or 5 seconds, and lag can only jerk that time upwards.

In a perfect world with no lag, animation lock would be an acceptable thing to plan around.