People who say Terra's voice and body language didn't fit her in Dissidia...really just didn't get the point of Terra's character at all. Some people actually viewed her as this unstoppable bad ass killing machine after her amnesia stage, for example...um, no? She was still clearly a timid, soft spoken character (which her Dissidia character is), just had more confidence. Its also people who think that they based Terra "only off the first 2 hours of the game, and missed all her development!"
Um...no shit? That was kind of the point; they weren't branching off from her development, it was more a character reboot. Cloud, Squall and Tidus had the exact same effect on them, but people ignore it cause hey, who cares about those 3? They get enough attention. People whine about "Why is she hiding behind Onion Knight when she's the one whose protecting children!?" ignoring that Onion Knight is NOT the same as the children of Mobliz (Who are implied to be younger and, you know, civilians), the whole lack of the Love factor in Terra's character (something clearly dropped cause its incompatible in Dissidia, replacing it with "Dreams" which fits better while still consistent with her character)
Basically, what it comes down to is people don't know the characters they're fans of, and Dissidia proved that a lot of supposed "Terra fans" don't actually like her for what she is, but like her for the false image they made of her. I think FF7 characters are the strongest example of characters liked for all the wrong reasons. I've seen plenty of other characters get equated to minor factors of their personality as being the source of their development, like Zidane being "nothing but a ROGUE LIKE LADIES MAN!" No, that's Edge (ok, Edge is also a hot head, but be quiet), Zidane is actually the Fun Loving, Obsessed with Helping People guy, constantly worried about his friends guy that Dissidia paints him as.
Or Cloud? He was always a rational, introverted guy that Dissidia painted him as. Yet, people remember him being somewhat like the Kingdom Hearts/Advent Children variant of this "Anti-social, bad ass action hero!!!!" Ok, congrats for completely missing the point of Cloud's character, since you described SQUALL more or less dead on.
I've heard a better complaint being that Terra's VA was hurt by bad voice direction, not necessarily the voice itself being a bad fit for her, which...personally, I saw nothing wrong with it (or anybody in Dissidia really. I'll grant its not Square's best case of VA, such like Crisis Core was definitely overall better at this execution, but it certainly wasn't horrible), but its a more reasonable complaint at least, since its at least not randomly painting this false image of Terra to claim it didn't fit. There were some awkward moments where trying to match the lip sinking made the english dialog sound a little off ("I won't let you...get away with it!" comes to mind. The odd pause in the middle to match her lip movement makes that line come off as awkward, where as in the Japanese, it was more appropriate due to the words being said.) Obviously, characters like DK Cecil or Garland, who cover their mouths entirely, have no excuse if they ever pulled that shit. You'll note Battle Dialog, including the Victory, Loss and Challenge quotes, are all somewhat better quality and more consistent in this regard cause there's no Lip Sinking to match up with.
My general point is...her actual voice and the way Dissidia displayed her were actually consistent with FF6. A lot of people probably were upset that they took more a character reboot route, making her appear more Damsel-in-Distress like for the plot scenes rather than the strong willed heroine she is portrayed as in the game's ending. They also act like she was totally cowardly and running away from everything...
That's kind of funny cause it was Onion Knight, her "Guardian" who was the coward. She even tries to call him out on it (just his Enthusiastic, Outgoing personality kind of overpowers her soft spoken one) in his scene with Ex-death. The scene with Kefka wasn't her being afraid, that was Onion Knight jumping in before she had time to react, and she certainly didn't run away from Cloud pointing the buster sword at her (actually, if anything, she told Cloud TO run, as she was afraid what she'd do to him, not the other way around.)
...yeah, I kind of went off on a big tangent, but lets be honest here; people who say it didn't fit...mostly just don't really know the character they're talking about. Its like how I initially thought Lymle's voice in SO4 was stale and dry, kind of lacking in emotion...but then I read her in-game bio and recognized that was intended, and was willing to accept the voice more after that.
-----
Regarding the "Is Voice Acting bad these days" comment? It...really depends on the scene. There are some instances where voice acting doesn't really do much to help a game. FFTA2, which I'm playing now, there's really not much TO show in terms of emotion, personality, etc. You can get a good enough impression on the tone and style the character is speaking just based on the dialog.
But then we have scenes from Crisis Core...I can't honestly say that Zack would have come off anywhere near as effective as he did without voice acting. Or really, anyone in Crisis Core. Genesis' constant poetry would have been MORE annoying without voice acting, actually, cause then you're constantly reading random poetry, not having the appropriate visuals to get an idea of what the point of it is.
And then voice acting adds flair to gameplay elements. Valkyrie Profile, for example, always felt more interesting for fights cause of the Voice Acting; yeah, true, gets cheesy hearing the same "It shall be engraved upon your soul!" over and over again...but at the same time, there was that kind of charm to it. Hearing characters go all "HAVE AT THEE!" in their unique styles at the beginning of each fight helps mold their personality, as does their own victory lines. Replace VP with other games that did the same thing. Heck, even little nuances like FF10 Final Enemy kill quotes, like Tidus' "Seeya!", Wakka's "Booya!" or Auron's "Farewell" just give the cast that much little extra coloring.
So yeah, really depends. Games like Tales of Eternia, the voice acting, even ignoring its horrible quality, didn't feel like it served a purpose in plot scenes, since Voices without action kind of don't mesh well, which is exactly what ToE was. But then we have these full interactive scenes, and...well...would any of those SHC scenes be as hilarious without the voices to go along with the antics?
Note that activity does not need to be full CG characters ala many PS2 games; simple still shots with exaggerated motions like, say, Disgaea, work well too...heck, Disgaea is a fine example of that for a number of reasons.