That's absurd. A job is powerful on how you build your character. That was the main controversy issue with the jobs on XI (and even abilities that were shockingly influenced by the activities of ballista) was balancing every other job so that others wouldn't get jealous. This is different. They can't nerf something you worked on FFXIV compared to XI. That's another dedication change you'll have to go into.
Say for example you're a Maurder and you're supporting craft job to repair and make your own weapons is black smith. You find out that maurder gets nerfed on certain performances or attributes that makes you no longer wanting to play it anymore. Then you decide wanting to go onto archer with the supporting crafting of carpentering to do the very same recycling method as maurder.
Would you want that happening? I sure as **** don't.
Either you're being bias on purpose or you don't understand MMORPGs and how they work. Although the word Nerf has natural negative conotations this is usually used instead of balanced when the changes caused the class in question to perform in an inferior way to other simillar classes.
If you have two calsses that only do damage and one of them is changed so that it now does the same damage as the lower class, this is not Nerfing, this is balancing. Nerfing would be if playing each class at their best you werent able to do as much damage with one as with the other.
Although I can't understand what you mean by your exemple I'll try and put my own forward:
By reducing the ammount of of VIT HP gained from VIT SE is lowering the benefit of VIT to all classes but the ones that actually tank, since they are the ones supposed to be taking damage and Phisical defense and Magic defense were increased.
This way, classes that arent supposed to be hit get less benefit from VIT (from HP increase) while tanking classes still got an increase in defense.