Sometimes you have to read between the lines, sometimes you don't. Many classic D&D detractors claim that game too often succumbs to the "kick down the door, kill 'em and take their stuff" routine. At first glance, the dungeon element seems to support this claim. However, it is often the case that, when focusing on the whole, the reader will often ignore the details. I believe this to be unintentional, in most cases anyway. But is classic D&D such a game? Let's take a look at the following from the Moldvay basic edition:
When a character has 9-12 in Intelligence, he knows how to speak Common and his alignment language. When a character has 13-15 in Intelligence, he knows how to speak the two aforementioned languages plus one of his choice. With Intelligence of 16-17, he knows two additional languages. And with Intelligence of 18, he knows three additional languages. Alright, it seems fair. A human with high intelligence would know how to speak common and, say, Lawful and elvish and dwarvish. But wait! The list of languages from which the player can choose includes such oddities as kobold, hobgoblin, dragon, harpy, ogre or pixie. Say what? Do I really need to know how to speak kobold when happily hacking away at the little buggers? Perhaps, I'm the kind of guy who enjoys insulting their mothers in koboldish while cutting of their heads. Then again, you never know when you need to know kobold to read a kobold magic book. But that's what Read Magic is for. At first glance, this rule would seem at odds with the whole hack & slash concept of the game. Or is it?
A few pages ahead, the rules state: "Experience points are also given for monsters killed or overcome by magic, fighting or wits." I emphasized the last words. Yes, apparently you can earn experience not by just killing things and taking their stuff, but by actually pitting your wits against the monsters. This suggests a number of things which are implicit, rather than explicit: First, the word monsters is a misnomer which tends to devaluate the intelligence of the opposition. We consider monsters things with no rational thought, things to be killed. Second, the phrasing of the sentence implies that monsters can be, and often are, intelligent, or else overcoming a challenge of wits wouldn't be a challenge at all and, therefore, not worth experience points. Third, there are options other than fighting our way around a dungeon. Most creatures react purely on instinct (such as gelatinous cubes or giant spiders, or do they?) but others have a rather organized society even if only implied. Orcs know how to use armour and wield weapons; they can fight in an organized manner, as do kobolds, hobgoblins, etc.
Considering what I wrote in my last paragraph, a character benefits with high intelligence. Surely, when running into a dragon, the character who knows how to speak the creature's language is given the opportunity to shine. The encounter need not end with a total party kill. Dragons are vain and egotistic. They can cajoled and tricked with smooth words as Bilbo did in The Hobbit. It is up to the DM to provide the necessary challenges. The dungeon then becomes more of a puzzle with situations where roleplay is as important as combat skills.