I suspect that part of the reason films based on games are more difficult is that games are not really story driven. They're innately interactive. They are about environments in which the players interact. Fans of games are fans because they play the game. Fans of a book read the book. Fans of a TV series watched the series. Fans of a comic series read that series. It's hard to verbalize why that makes a difference, but it does seem to.
Didn't you stop buying games a decade ago because they became too narrative driven and you didn't like it?
Mostly I stopped buying games because I don't have the kind of time to play them that I used to. But you are correct that I've never been a huge fan of games with story "rails", so to speak (always more preferred more strategy/tactical games or open world games). I'm not sure Warcraft falls remotely into that category though. In fact, I'm quite sure it doesn't. But if someone were making a film based on one of those types of games, they'd run afoul of not having nearly enough time in a single film to include the entire story, which would certainly result in fan rage.
Eh. And even games with tight stories still tend to have multiple character choices along the way. Again, that's tough to implement as a film. You either stick to a single instance of the story (specific character choices) and get stuck with a smallish fan support (cause honestly, my other beef with those games was the almost universally moronic nature of the plots within, which means only people who are *really* fans will want to see the film, and half of them will be pissed at the character choices the film goes with). Or they deviate completely and get fan rage from that too.
Ironically, I actually think your best odds would be a film set in a more open game setting (like any of the MMORGPs out there). So Warcraft had as good or better a shot as any. But, as I mentioned above, you actually have to write a good story
. It honestly seems like the folks who write the scripts for films set in game universes kinda phone it in or something. It's like they think that the fact that it's set in <insert popular game world here> will make audiences forget that the plot they wrote is moronically simplistic and trope-laden. I have no clue what the plot for Warcraft is, but I'd guess it's got the usual mix of world threatening danger, band of unlikely heroes rising together to fight it despite differences in background, race, class, national identity, etc that might otherwise make them adversaries, a mix of poorly defined magic/tech/whatever to drive the plot forward as needed, random luck that gets them through, and probably every other stereotyped story element that we can think of.
Funny thing is that you can include all that stuff and still have a great film. You just have to get the right balance. I also firmly believe (cause I've seen it too often) that many writers mistakenly assume that if the world you're writing for requires suspension of disbelief for some form of magic/tech, that this means the audience will suspend disbelief in basic plot elements as well. I'm not sure what it is about a sci-fi/fantasy setting that makes writers do this, but they do. And the result is gaping plot holes that the writer thinks aren't a big deal because "magic/tech", but the viewers will hate because "magic/tech doesn't work like that". Dunno. Just a general trend I've seen.