I can't speak too much for BG1/2 since I'm not sure I was even alive for those ad campaigns, and if I was I certainly was too young to be aware of their existene. But I will point out that the landscape of rpgs have changed. having played part of BG1, the companions there are shadows of what you get in most party-based rpgs these days. their content is miniscule, they clearly were never really meant to be a draw the way they are now. And with the MCU example, yes Kang is featuring heavily in the marketing, but this is the third movie of a three-movie series that's had the same central cast the whole time. Anyone watching that movie is likely to already know the main characters and who they are, so Kang is the new factor that the story is turning on. Plus there's the added complication that Kang is going to be a factor in the wider MCU. This would be more like if Ant Man 1's marketting had revolved around Yellow Jacket. You're right that film and game marketting is often similar, I just think the MCU is too different to be a good comparison here. Even with Thanos, he was foreshadowed in a post-credit scene in the first Avenger's movie, which I would again consider very different from what Larian's doing.
The fact he's been a non-entity for the bulk of act 1 and that he's still going to share screentime with 2 other villains and then the Absolute itself just makes me think he's not going to be all that significant in the end, just a boss we end up having to defeat eventually. I can't see a meaningful relationship building between us and him or any villain really. Act one of a story is where these things are meant to start, and for me at least, it's off to a very poor start and I don't expect it to improve. I don't actually care about him at all. I'm pretty disconnected from the story of this game in general though to be frank. It's an enjoyable play experience but so far act one has failed to impress me or make me feel like it stands out in any way.
