The real joy of this entire thread is discussing player education.
An obscure trap/puzzle/insta-gib encounter can run from relative to being an axiom; for example, in a game that has a bunch of trash trap builds (think of a wizard in D&D running full strength and using int as the first dump stat) an encounter that is insta-gib is going to look pretty different.
Since this is the case, it's a nice exercise on map design where you're trying to educate the players as much as possible without hand holding them and at the same time providing meaningful encounters with whatever constraints the system has -- DSO is nice in that mostly everything is flexible but at the same time because of that flexibility you have to account for a wider range of player behaviors that in a strict class based system you wouldn't worry about.
I think one thing that games can do to help ease the adjustment is to add an auto save trigger before the earlier ambushes. This takes the sting out of early experiences while still allowing the player to learn.
That aside, OPs comment basically amounts to, "I'm intentionally going against the design of the game and not taking the steps (having high initiative and scouting) to prevent disaster, then complaining when I don't get away with it." There isn't an explicit problem with the game, just a player who didn't take the time to understand it and then got mad about being punished for his ignorance.
