dtgreene: In my current Dragon Quest 9 playthrough, I recently fought a boss that occasionally uses an attack that hits the whole party (no multitarget healing for the player at this stage of the game), and it used that attack twice in a row. I think I had to revive a character (though, fortunately, Zing worked; anyone whose played any DQ game other than the first two will know what I mean here).
Also, in an earlier boss fight, one that's supposed to be easy, two of my characters got paralized, putting me in a bit of a pickle. (Good thing I give everyone a cure paralysis item!)
Then again, I remember cases like in Dragon Quest 2 or Final Fantasy 1 where enemies would hit my entire party with status ailments and not let any of my characters get a turn before they get slowly killed. I would argue that this is worse than having your party wiped out by a mass instant death attack; at least the later case is over quickly! (The latter event can happen in both games, though in the FF1 case it's more likely in early remakes (WSC/PSX) because of an AI change.)
There's also, in games where you have AI controlled party members, cases where they waste all their MP on easy battles, leaving none for when you need it. Or, worse, when they use your consumables, something that, IMO, the ally AI should not have access to unless the player explicitly enables a setting that gives them access.
Some of the things you said here sound more like poor design choices than a cheating AI.