From pp 202, 205:
Orcs worship Gruumsh, the one-eyed god of slaughter, and are savage, bloodthirsty marauders. They plague the civilized races of the world and also fight among themselves for scraps of food and treasure. They love close combat and plunge furiously into the thick of battle, giving no thought to retreat or surrender.
Within what passes for orc society, there are orcs that fill special roles. Eyes of Gruumsh are orcs with a special connection to their fierce god. They offer sacrifices, read omens, and advise the tribe’s chieftain of Gruumsh’s will. Orc bloodragers are tribal champions feared for their strength and ferocity, and they also make excellent subchiefs or bodyguards.
Orcs often fight alongside ogres, and they can be coerced or bullied into serving any dark overlord or wicked monster powerful enough to command their obedience. . . .
Orcs favor hills and mountains, places pocked by caverns easily turned into defensible lairs. Bloodthirsty marauders and cannibals, orcs venerate Gruumsh and thereby delight in slaughter and destruction.
Orcs don’t build settlements of their own, instead improving existing shelters with crude fortifications. They prefer to settle in natural caves or structures abandoned by other, more skillful races. Orcs can manage simple ironwork and stonework, but they are lazy and grasping, preferring to take by force the tools, weapons, and goods other folk make. . . .
Orcs band together into loose tribal associations. The strongest individual in a tribe leads as a despotic chieftain. Individual bands within a tribe might wander far from their native lands, but they still recognize orcs from the same tribe as kin. . . .
Orcs often demonstrate their faith in Gruumsh by gouging out one of their eyes and offering it as a sacrifice to their one-eyed god.
According to myth, Corellon shot out Gruumsh’s eye with an arrow. For this reason, orcs hold a special hatred for elves and eladrin.
Compared to the AD&D MM, this has more information about Orcish religion and social organisation. It has less information about demographics and preferred weapons (though the latter can be easily inferred from the stat blocks). The only bit of colour about Orcish society in the AD&D MM that is not replicated in the 4e MM is that "Known orc tribes include the following: Vile Rune, Bloody Head, Death Moon, Broken Bone, Evil Eye, Leprous Hand, Rotting Eye, Dripping Blade".
Here is the 3.5 MM (pp 203-4):
Orcs are aggressive humanoids that raid, pillage, and battle other creatures. They have a hatred of elves and dwarves that began generations ago, and often kill such creatures on sight. . . .
When not actually fighting other creatures, orcs are usually planning raids or practicing their fighting skills. . .
They enjoy attacking from concealment and setting ambushes, and they obey the rules of war (such as honoring a truce) only as long as it is convenient for them. . . .
Orcs believe that to survive, they must conquer as much territory as possible, which puts them at odds with all intelligent creatures that live near them. They are constantly warring or preparing to war with other humanoids, including other orc tribes. They can ally with other humanoids for a time but quickly rebel if not commanded by orcs. Their deities teach them that all other beings are inferior and that all wordly goods rightly belong to the orcs, having been stolen by others. Orc spellcasters are ambitious, and rivalries between them and warrior leaders sometimes tear a tribe apart.
Orc society is patriarchal. Females are prized possessions at best and chattel at worst. Male orcs pride themselves on the number of females they own and male children they sire, as well as their battle prowess, wealth and amount of territory. They wear their battle scars proudly and ritually scar themselves to mark significant achievements and turning points in their lives.
An orc lair may be a cave, a series of wooden huts, a fort or even a large city built above and below ground. . . .
The chief orce deity is Gruumsh, a one-eyed god who tolerates no sigh of peaceability among his people.
This does not differ a great deal from the 4e stuff. The 3.5 text talks about the love of ambushes, but - unlike 4e - it does not explain
why Orcs hate Dwarves and Elves. It tells us about rivalries between warriors and spellcasters, but doesn't tell us who these are or what their social roles are, whereas the 4e material does address that. 4e drops - I think for fairly apparent reasons - the discussion of women as property of men. But it does mention cannibalism.
I don't have the 2nd ed AD&D or 5e descriptions to hand (though I have reviewed the 2nd ed AD&D discussion of creatures in other threads, and think the claims to its extensiveness are greatly exaggerated). But given the above comparison of AD&D, 3.5 and 4e, I think it's simply not true to say, as you did, that
I mean, unless you also think that AD&D and 3E "flipped the bird at lore in general".