Is this game really so different that a healing Conjurer isn't going to want to keep up Protect/Shell while healing, or a damage Conjurer isn't going to want to cast the nukes the enemy is weak to, or a Thaumaturge isn't going to want to enfeeble the target? Giving a class a different name doesn't make it magically different from its classic incarnation.
Yes, because a Conjurer has a choice between being a healer or an elemental damage dealer, or a bit of both. You could not change Conjurer into a "White mage" without removing the nukes. Likewise, simply changing the name to "white mage" without removing the nukes would damage the image of "White mage". And if you're not going to stick to the traditional definitions, why change the names at all?
I don't think it's inviting FFXI-2 mechanics, mostly because the names themselves are not the exclusive domain of FFXI; they're staples of the entire series. Their explicit absence actually makes FFXIV more of a black sheep than it already is. Like many things in the game's design, their exclusion seems to have been nothing more than an attempt by Tanaka and co. to further distance the game from the franchise it's a part of. I can't say I agree with that direction.
You're right that the names are not staples of FFXI but of the series as a whole. However, FFXI is the only other online
Final Fantasy, and an online game must conform to different rules than single player games. Single player Final Fantasy games have a nearly limitless potential for unique gameplay mechanics, but online games need
to have certain features to be successful. Again, I'm not saying it isn't possible to completely redesign FFXIV from the ground, but that is what would be required in order to faithfully use traditional names without feeling like FFXI-2. I'm also not saying a complete redesign is a bad thing. However
redesigning the game simply to use traditional names is
a bad thing. If they do redesign FFXIV from the ground up I hope it's to make this game truly fun rather than a justification to rename Conjurer to White Mage.