I'm seeing that the logic isn't "It's too difficult for players to comprehend," but rather "It forces certain classes in certain situations."
With the current FFXIV, while it isn't always optimal, as long as you have a tank, a healer, and some DPS, you can do pretty much anything. Restricting certain actions to certain moves used by certain classes means that players who don't LIKE those classes are forced to use those classes for those purposes.
For example, let's say player A really likes playing lancer, and he really likes crafting.
It's a pretty well-known fact that certain recipes for gear for lancers require aldgoat horns (horn scale armor, anyone?) and Player A wants to be self-sufficient and make the gear himself.
Well, since he uses spears, he can't get the horns. Sure, he could buy them, but he can't get them himself and thus can't be self-sufficient.


Another example. There's a boss who needs to have his legs disabled in order to prevent an OHKO charge attack. Your group is therefore FORCED to bring a monk and/or bard for this fight, since they're the only ones that can disable lower limbs.
Conversely, if the arms need to be broken, you MUST bring a DRG to deal with one limb, and either a WAR or PLD for the other limb.
This is called "character select forcing," something 2.0 was specifically designed to NOT have. They've said numerous times that they'd ideally want all content to be doable by any configuration of DPS, tank, and healer.
The dev team doesn't think we're idiots, but they DO think we complain a lot. And they're not wrong. Having a system that promotes character select forcing just makes the game unnecessarily convoluted and doesn't gel with the way the game system works now. Since melee classes use combos now, pretty much every attack will get used so just adding "breaks" to skills would be pointless as nearly every skill will eventually get used in a long enough fight.

Oh, and having to knock off a horn from a goat to get it is stupid anyway. It's dead. We can pull it off ourselves. If anything hitting it with a sword would be more likely to damage it beyond use.