Quotes / Our Dwarves Are All the Same

Dwarves typically consist of seventeen main organs: the beard, the boozehole, the gratuitous Scottish accent, 13 livers and an axe.

Moreover, much like his elves, they aren't very distinct characters. Someone's said once that there are no dwarves in fantasy, just one dwarf copy and pasted all over with a few details changed, and in no other fantasy fiction I've seen truer evidence of this.
from Candlekeep forums, on R. A. Salvatore's dwarves

Gimli: Think about it. What is the defining characteristic of dwarves.
Aragorn: Low charisma?
Gimli: I mean besides that.
Legolas: Bearded women?
Gimli: Not that either.
The GM: Rampant alcoholism?
Gimli: No! Well, maybe a bit. I'm talking about the fact that dwarves are lawful!

Wow, a dwarf that smells like a brewery! You never see that ANYWHERE.

Bodhan: I've been looking everywhere for you, Messere. If only you humans didn't all look the same.
Hawke: We can't all be short and bearded like your people, Bodhan.
Bodhan: Indeed. It's quite a shame, really...

Dwarves are one of the easiest races in D&D to roleplay. They have well-defined personalities, and it's easy to imagine a dwarf character in your mind as you play. Everybody knows how dwarves are supposed to look and act. Accordingly, making a dwarf character is often a matter of deciding how much you want to play against type. You can be a doughty dwarf fighter, a sneaky dwarf archer/rogue, or even the vanishingly rare dwarf sorcerer.
Races of Stone, a Dungeons & Dragons supplement that discusses dwarves in depth.

Ideally humans will end up with enough parameters to end up like various different civilizations, and the other civilizations will probably become more alien to humans as humans take up more of the slack. Dwarves are an exception to that since they should keep some familiarity to be easily playable, and they should continue to exemplify the highs and lows of human craft and inebriation.
Dwarf Fortress creator Toady One, explicitly indicating how and why his dwarves will exemplify this trope.

Cleric: Does he have any distinguishing features?
Haley: Well...he's short.
Celia: He has a beard.
Haley: He wears heavy armor.
Cleric: Ummm, OK... how about any unusual personality traits?
Haley: He likes beer.
Celia: He has an accent.
Haley: He worships Thor.
Celia: And hates trees!
Cleric: Can you tell me anything about him that differentiates him from every other dwarf?

Now Dwarves, Sire, are like angry beards on legs. Angry, beer-soaked beards on legs.
Gnarl, Overlord

I'm a dwarf!
Skull, providing his new D&D character's entire backstory in PvP

Player Character: I thought Dwarves were short with long braided beards.
Zaid: What? That's just an old stereotype! Most dwarves are normal height and prefer not to have ridiculous facial hair.

When I were but a lad, my father, the King, taught me three things:
Never accept a gift from an Elf.
Never trust gold that glistens in darkness.
Never forget a grudge.
On his deathbed I swore to uphold these values to me own dying day, and Grungni willing I will.
King Alrik Ranulfsson of Karak Hirn, Warhammer

Born underground, grown inside a rocky womb
The earth is our cradle; the mountain shall become our tomb
Face us on the battlefield, you will meet your doom
We do not fear what lies beneath
We can never dig too deep!

I am a dwarf and I'm digging a hole
Diggy diggy hole, diggy diggy hole
I am a dwarf and I'm digging a hole
Diggy diggy hole, digging a hole...