While I understand the point you're making (at least I think I do), I'd have to disagree with the conclusion being drawn from it.
Yes, getting into a fight that can seem impossible to beat at first can be a frustrating experience but at the same time, it forces you to think of ways around it. An ambush is, after all, a premeditated engagement in which one side has stacked all of the odds in its favor and has the element of surprise, they're supposed to be nearly impossible to overcome.
D:OS SPOILER ALERT!
I know the ambush you're talking about and it had the same effect on me that fighting Braccus Rex in D:OS had when he drops a meteor storm on your tightly clustered party the moment the fight starts and TPKs your entire group before the "FIGHT" banner goes away. At first I was like, "What happened?"
But then my brain starts churning and I think of splitting up my group before fight starts and stacking their fire defenses to survive the initial volley and the strategy developed from there, like getting rid of the Ghould-That-Used-To-Guard-The-Lighthouse first because his poison clouds kept a constant synergy going with all the fire and kept healing Braccus and the Twins-Joined-By-Fire.
/SPOILER!
The point behind that kind of engagement is to keep you grounded. It breaks you out of the mold of "run in, slaughter EVERYTHING!" that you can easily get into when every fight is easy to see coming a mile away and you can use the same general strategy(ies) to overcome them. It forces you to think outside the box and tests your ability to overcome a situation that is completely stacked against you.
I may be alone in this but I am glad things like that are in this game and I hope they remain.
