1.) Even nondescript grunts, yells, and chuckles can be off putting or abrasive. So far I think they've done a decent job in this regard. The voices also seem to be non-region specific and cut from scratch (not Wilhelm screams) so it'd be in their best interest to continue in that trend. Slightly off topic but if I'm not mistaken 2.0 will have each supported language represented in at least the CS's voice acting. If they are bad voice actors people will just choose to turn them off.
2.) Some suggestions so far include the random wisecracks you could come across with Lulu in FFX. It didn't happen every time but when it did it wasn't too jarring and did add some flavor to the sound during battle sequences. A bad example, as has already been represented, would be like Snow's constant statements of gratitude every time you would heal him. Every once in a while is fine, especially if you have certain code parameters combined with a random modifier for example... A character has critically low HP, when healed into a safer zone of HP a statement of gratitude may be triggered if the randomizer deems it so. The same could be done with spells as well. If you could write the code to express the context of the situation to show they
need to be said and then throw a random element in there to help decide whether or not the words
will be said then I could see myself not needing to turn them off. I do appreciate the little "haha" my character makes when they evade an attack, especially on Pugilist. The audio cue combined with the visual 3D text not only enhances the aesthetic but also adds to the play mechanics as well. Unfortunately when I'm in a party, it's difficult to tell who is "haha"ing, which brings me to ...
3.) You should have the ability to toggle specifically what you want filtered, just like text in the chat log. To all those that say you should have the option to turn voices off; you already have that option: Configuration>Audio>Decrease the Voices slider. The problem with that is it lowers the volume of all voices (cutscenes not included). As I've stated earlier, I believe what they already have is pretty decent and I wouldn't want to get rid of that just because more annoying phrases were implemented. If they give me the ability to specifically filter the phrases or context in which certain phrases are uttered I'm totally fine with that but don't force me to completely drown it all out when some of it is actually quite nice to hear.
Here's an audible example of what happens when you have a whole group of people announcing every non basic action they're doing. Considering the faster based combat in XIV, it wouldn't be much different. If anything it might be worse considering eight person parties and the eventual massive scale PvE content they might bring to us in the future.
Tales of Symphonia
I've personally adapted to just shutting out the sound effects from video games but I don't expect others to do so nor do I agree that its necessity, even on my own accord, should be accounted for from a sound design perspective. If you're going to implement something that you think the audience will just end up "drowning out" then don't implement it in the first place. On the contrary, if you think it will definitely enhance the gameplay and aesthetics then by all means move forward, but even when you do move forward; do so with caution and leave the option to experience it in the hands of the individual player. If anything this game needs more toggle options. They've done a great job with things like Popups, help text, and the /display options but they could certainly do more in the toggle department when it comes to the visible real estate on the screen.