Really?
When you have thirty years, and tens of thousands of pages of modules all pretty much saying the same thing, written by dozens, if not hundreds of game designers for the same system, that doesn't actually count as evidence?
Let's examine a few of these modules you're talking about. I'm going to cherry-pick a few here, just to make my point- which is that they didn't all assume that combat would be the be-all and end-all of the adventures.
So- the A series.
One of them very strongly encourages the pcs to be sneaky, deceptive and diplomatic, because you're entering a friggin' enemy city. You go berserk with the combat? TPK. Was there combat in there? Sure. Of course there was. But IMHO and IME, the assumption was "You better avoid straight hack and slash, or you're dead."
Then you have A4, where you start with almost nothing other than a loincloth, trapped in a monster-ridden dungeon. I don't know about you, but my group found, when we played it, that we
couldn't out-fight everything under those circumstances. We
had to be sneaky and tricky to get through it.
Dwellers in the Forbidden City has lots of combat opportunities- but those same opportunities are also roleplaying/interaction opportunities. Heck, there's a whole subsystem introduced so that a pc can have a nonlethal wrestling match with a tribal leader. And the whole module is a shining example of exploration as the major focus- just look at the map of the city! Too, there are so many new monsters and things to encounter, this is probably one of the best examples of a "sense of wonder included" module, and all those new things? Exploration. Discovery. Combat, maybe, sure- but that's absolutely not the emphasis. Exploration is.
What about
Against the Cult of the Reptile God? It's all about investigation. You don't have a clue what the problem is initially, and need to figure it out. You can't do that by cutting down all the villagers.
Steading of the Hill Giant Chief is perhaps the quintessential example of "hack and slash will get you killed". You had to be sneaky or die. A frontal assault ruins any chance of success that you might have, unless you are VERY lucky and the DM is extremely soft and generous.
The Secret of Bone Hill is a small sandbox, including a few dungeons, but it also includes significant details on an entire town, not to mention a temple of gambling. In fact, I'd bet that many groups (several of mine included) spent as much time at that temple as they did under Bone Hill itself.
The Assassin's Knot is a straight up murder mystery. Sure, there's combat, but it's absolutely NOT the focus. Investigation, once again, is what it's all about.
Tomb of Horrors is all about exploration, too. There are only about 3 combat encounters to be had in it. It's deadly, yes, but it's not deadly because of combat.
The Village of Hommlet spends nearly as much on detailing the titular village as it does on the local dungeon, and so much of it is focused on figuring out who you can trust and turn to for aid that I gotta give that one another high level of "not combat focused".
All three of the D modules-
Descent into the Depths of the Earth, Shrine of the Kuo-Toa and
Vault of the Drow- are also heavily focused on exploration and roleplaying. Often, the encounters involved are tpks waiting to happen if you take the frontal assault path. The level of cultural detail given to all those places along the way is exquisite.
Lost Caverns of Tsojcanth typically took multiple sessions for the party to even
find the dungeon. Yes, there was a lot of combat after you got there, but exploration was a huge element of it.
The Lost Temple of Tharizdun pretty well assumes you're starting with a bunch of roleplaying and interaction with the gnomes before moving on to a massive combat, but then is full of exploration again. Heck, the entire
climactic section of the module doesn't have any combat in it at all!
Hidden Shrine of Tamoachan centers around an environmental danger- toxic gas- and attempts to escape it via exploring until the pcs find their way out. Yes, again, there is combat, but the focus is on escape, not killing things and taking their stuff.
The Lost City is full of different factions all hallucinating all over the place, and most groups are likely to engage in a ton of interaction, as well as exploration, as they discover an entire city in there. Combat? Sure. The focus? I think not.
And so on.
So, yeah, the modules don't exactly support "It's all about combat!". Some certainly do, but not all. And, in fact, almost all old modules have situations practically begging for non-combat approaches.