Vitriol isn't always unwarranted, people don't want this- and they're letting everyone know.
And I wouldn't call the majority of it vitriol. Just expressions of disappointment.
"Not too late to get Creative Assembly on the phone guys...#AlienIsolation2" -Twitter
"Why #AlienIsolation was such a great game and deserved a follow up game on consoles. #PS4 #XboxOne #NintendoSwitch" -Twitter
"But...that's...not what we wanted." -Twitter
"We thought it would be a sequel to Isolation...we thought it would be something worth playing..."-Twitter
"Wow! You gaming companies never learn do you?
Did you already forget the extreme backlash that EA and Blizzard got when they announced C&C and Diablo mobile games?
You are doing exactly what they did at Blizzcon! Teasing a new game and announcing that it will be Mobile only." -Twitter
"Not what I expected. Hoped for a AAA experience like Isolation and I'm hugely disappointed now...
" -Twitter
"I have loved the Alien movies and books for years. The first video game with #AmandaRipley brought me right back into the whole story.
We waited and we get a Mobile game. People don't invest that much time into mobile games. I still love Alien but I'm sorry, not a mobile game."
-Twitter
"Lame! I was hoping for a real successor to Alien: Isolation, not a mobile game." -Twitter
"Thank god another studio is working on an ACTUAL Alien game." -Twitter
The response seems pretty reasonable to me,
bearing in mind how most fandoms react to disappointing news.