There was a certain style the game had throughout and up until the release of Cataclysm, which was to say the old world. Certain mechanics I am familiar to and was fond of - paladin seals were iconic, rogues having to craft various poisons and harvest them, hunters having to find just the perfect animal companion of the type they wanted, having to time and check your pulls so you did not attract too many enemies, the pace of combat tended to be much slower - so they hold a special place in this feline's memory. Initially, when I first began, I knew so little of the game that I wandered and leveled by grinding, killing monsters which I was a bit stronger than and doing the odd quest I could figure out, selling the rest of the scrap and any loot on the auction house. This pattern of behavior actually allowed me to purchase not only a mount, but an epic mount as a nobody; I had stumbled into a taste of success. That only grew when the Burning Crusade was released and I discovered what raiding actually was. I shelved my druid then for a time, which was to say a mistake.
In general, older Warcraft felt more gritty and atmospheric, much more open too. I suppose this can be best described with massive locations in the old incarnation as with the Barrens, the Plaguelands, Stranglethorn Vale and so on. It was a slow going pace and you were just expected to discover things on your own and bring a party or friend wherever you could. Talents allowed you to, through even a bit of trial and error, figure out what a character was to even be.
As for Dungeons and Dragons, they made a variant of the game that used rules and lore from Warcraft. Warcraft itself has a great number of obvious inspirational choices based off the game, just as the same could be said for the DOOM franchise.