While I can agree that some dialogue during important plot relevant boss fights would have been nice, I am actually happy the party stays quiet because I find chatty party's to be really annoying. I will physically wince if I have to hear Rikku say something stupid and bubbly in the beginning/ending of a battle in FFX/X-2 because it aggravates me. I'm fighting monsters, I don't need to listen to the parties lame jokes and one-liners. I have similar issues in the Star Ocean series. If you want to see a game that does party dialogue during gameplay well, I would say The Last Story comes close because they actually have conversations, not declarations against bad guys or silly one-liners you'll hear a million times for the next 40 hours. If you miss the dialogue, the conversation is never repeated again because it's only relevant at that point in time. Dialogue in random battles just makes me more painfully aware of the fact I'm playing a game and this battle isn't worth my time, because the party generally is mocking the battle anyway.

So I would say the lack of dialogue was one of the game's strong points actually. Vaan already irritates people as it is, he doesn't need some cheeky one liner to say in battle to make him more irritating like another blond protagonist. Not to mention Balthier would be more hokey if his Bond One-liners were said so often since he already has this schlick in the story proper. The rest of the cast doesn't strike me as the type to say lines either, I mean Basch, Ashe, and Fran don't strike me as the types to say witty things in battle and having them proclaim some "heroic" proclamation just undermines their characters. Honestly, the dialogue thing works in silly anime -style rubbish that is Toriyama's titles, but doesn't work so well in Matsuno's more serious and mature world of Ivalice.