The RPG genre as such evolved, too. Let's take a look at Lands Of Lore I or Eye Of THe Beholder, for example - that's pure "dungeon crawling" at its best. Even the Realms Of Arcania games have that.
And inside of a dungeon, there's only one thing : "fight forwards !".
No social interactions, no crafting, no quests, even. Yes, not even quests as such.
I don't know who invented the "Quest" as something that's been scribbled down in an journal, but at least there did exist things one had to keep in mind as things to do - and to scribble them down on the own sheet of paper, bevore the computer. Now, the Journal is within/inside of the computer, and modern games keep track of Quests on their own.
Same with Maps.
So, from this perspective, these "Action-RPGs" are nothing but "open world dungeon crawlers", where the open world replaced the dungeon - and in some cases it's still a dungeon.
But - what differs games like Titan Quest, Sacred etc. from Lands Of Lore I and Eye Of The Beholder is the fact that fighting takes place in an completely different style.
Simply, because the view is different now. You don't look into a dungeon like in Dungeon Master - front view - but you look at an open area or into a dungeon from above - and that makes the fighting style a LOT different !
Plus, the Multiplayer part. Dungeon Crawling as an multiplayer game ? Not a good idea. And at that time, no-one from the "multiplayer crowd" even wishd so. Simply because there wasn't any distinction between the view of the first person in a group (the group leader) and the second, third or fourth.
And because the fighting style was changed with the view onto the battlefield, it could become much faster then, too. Because you had an much better overview, could evade spells and arrows, could even use the terrain to your advantage ("kiting").
Action = adrenaline, imho, which means on the other hand that "slow RPGs" = no adrenaline. They are for people who like it slow, who don't like combat that much, but might prefer rather puzzles and stuff that needs your full concentration. Rather that than the ability to quickly move the mouse (and earn money with that through E-Sports).
Remember that puzzle in Drakensang 2 where you had to free the "mermaid" ? I wonder how much time the bestest and fastest E-Sports teams would need to solve that ... Each member of them individually ...