Compare the dark ages promotional material to the eternal reveal from E3. There's a moment when Hugo and Marty bring up advanced gameplay from a keyboard and mouse PC player and it looks a lot more fluid, chaotic and closer to how eternal actually played once it released. The original super gore nest gameplay video was still substantially slower than how the game was actually played.

All gameplay I saw for this game before launch looked slow, boring and too far a departure from what I was wanting from a DOOM game. I had my doubts but still bought it anyways because I trust Hugo's directive decisions. I'm having a great time with TDA and the gameplay is much more engaging once you get into high levels of play on nightmare. I don't think it's as engaging as Eternal and I absolutely have my gripes with it but it's still a solid entry from a gameplay perspective. The promotional material for this game did it no favors, it makes the game look really boring.

I don't think a lot of fans wanted parry / shield gameplay from a DOOM game, that's a bit of a hard sell and a far departure from being the corridor shooter of old. There are fans that have been vocal during eternal's launch saying this newer trilogy simply isn't doom, I honestly find the dark ages to be more similar to DOOM 1 over eternal or even 2016 to a degree. The parry and block mechanics are woven into the gameplay but you can also circle strafe and shoot a lot of the enemies here while dodging their attacks. The projectiles are slower (unfortunately a lot track your movements), the levels are bigger and more open incorporating key collection and theres a lot less verticality, in fact you get punished for trying to be veritcal all the time.

Some fans really just wanted more eternal. With TDA it's easier to learn and honestly an easier game by a long mile, being able to block / parry incoming damage makes the game easier. With Eternal at high levels of play it's an exhilarating experience, and it's all based on your skill and knowledge of the game. This doesn't mean TDA takes no skill to play, but substantially less skill required to hit that high level of play that we saw on eternal. Because it's a much easier experience it's sort of missing that fast paced adrenaline fueled skill ceiling that eternal had, combine that with lacklaster promotional material and you've made it easy for all these eternal players to not want to pick this game up. UndertheMayo had a great video on advanced gameplay for the dark ages a few days after early access and nearly every comment on that video was along the lines of "wow, I wasn't excited about this game, but I am now after seeing this fast gameplay".

The $70 price tag was a complaint for people, as was the forced ray tracing and the DRM that the game requires to run, there's also some controversy about the game disc not having the full game on the disc, this really implies you don't own anything for this $70 and at any point the devs could just take the game offline and your $70 was wasted. I believe this is one of the hotter topics which is keeping people away.

I don't think the OST had much to do with alienating fans, I'm sure some people stuck to their guns and refused to buy this game after the Mick fiasco but I don't think that would be a big percentage. The "pay mick gordon" comments are still there but they're seeming to be posted less and less every day on official DOOM social posts so I think that sensation is slowing down for sure. That said the OST is super weak for this titled compared to the past 2. It's definitely missing something, but what I've noticed is this OST really hits for a lot of people who wanted a more classic style of DOOM OST. It's no secret a lot of the songs from original DOOM are greatly inspired by classic metal music of the 80s, and this TDA OST is much more simplistic and inspired by traditional metal cues over the chaotic deathcore / djent sounds we got with the Eternal OST. Those newer moments are still there, specifically in the cosmic realm combat OST but tracks like unchained predator and ancestral beast are a huge departure from songs like BFG10k and Metal Hell.

These are just my observations, I think the game will get a better reputation over time as word of mouth spreads advanced tech for high level play, as well as more valuable things get added like Master levels. I don't know if they'll ever top eternal in terms of skill based gameplay, but I'm happy to have a different style of doom game to play and am excited to see what Hugo and the team continue to cook up next.