I don't think much evidence is required to show that Chaosium modules are built for violence. They generally assumed a final assault on the cult or monster, and often didn't give any other means of solving the plot. Actually, I think a lot of the authors assumed that the investigators would have access to tons of spells, and would just whip out a "Dismiss Whatever" at the end of the adventure. How the investigators would get these spells when the average lifespan was about 2.4 days, I have no idea.
In a lot of ways, the old modules were only half-written; there were gaping plot holes, odd assumptions, and no thought given to things such as "what if the PCs go to the police?" So they were a lot like the 1ed AD&D modules of the time, really. At any rate, more recent adventures (such as "Unseen Masters") have been a lot more fleshed out, but combat still seems to be pretty common (unless, as stated earlier, it's a "McGuffin" adventure).
I think a lot of this is just the limitations/boundries of the roleplaying genre. How many scenarios, in any game, end with the bad guy not getting attacked or somehow defeated by a plot-point? In heavy roleplaying campaigns, more attention might be paid to intrigue and politics, and there might not even be a "bad guy" per se (though there's still someone the PCs want to get, IME). But Cthulhu has pretty distinct hero/enemy lines: stop the Mythos forces any way possible in order to save the world (or at least an inbred, backwater portion of it). The fact that the heroes end up using the same, or even worse, methods as their enemies is just an interesting side effect.
For me, I always viewed Call of Cthulhu more as a mystery game more than a horror game. Instead of wading through the dungeon to get to the bad guys, one investigates and pieces together clues. This is far preferable to me IMO, but often my players aren't nearly as interested in things such as puzzle solving and criminology as I am. So, without focus on investigative and roleplaying elements, the game (or really any game) can easily degenerate into a splatterfest.
This sort of brings me to the point of all my insane ramblings- that Cthulhu, like every other RPG, needs to have the Keeper and players on the same page as to what sort of campaign it will be and where things will be headed. If the Keeper wants to run a campaign heavy on mystery and the PCs go around shooting all the people they're supposed to learn things from (I know I've been guilty of this before), then things aren't going to work out. Even for a game that is based upon a certain type of story by a certain type of author, there seem to be radically different interpretations as to how it should be executed- I've seen a lot of examples where the game is treated more like Resident Evil, for example. No problems here if it is, but it's the sort of thing that needs to be worked out in advance in order to avoid disasters.
So, to cut a long post short, yeah, the old modules assume a lot of violence. It sometimes takes a lot of work for the Keeper to change things, and the change of this assumption will also need to be communicated to the players, so that they know the expectations are different.
