The issue with BTILC was that the main character was an 'anti hero' and apparently they don't go down well over there (USA)
I thought it was great but then I'm British and we think (correctly) that the greatest character ever was the great hero of the Victorian age "Sir Harry Flashman VC"
You may have a point, but I'm not completely sold.
Same actor and director made Escape from New York with the lead being a definite antihero and it was a huge hit.
Back on the Thing, I think the gore and the grim and unrelenting mood harmed the film then, but now it is appreciated for these and more.
And there was plenty of competition: ET, Wrath of Khan, Blade Runner, Tron, and Poltergeist.
Is the film bleak? Hell yes. It is one of the movies I refuse to watch during Winter because how I feel going through that time in Iowa.
Maybe if it had been released at a different time it could have done better.