I don’t think it was ever a blockbuster movie that got great reviews. I don’t even remember it running in the theaters. I watched it when it came out on tape.
What’s a “tape”? lol
It came out about the same time as Kevin Costner's "Wyatt Earp." Remember that Kurt Russell, a lifelong hardworking Hollywood actor since childhood -- Walt Disney loved him and used him quite a lot -- had recently had the gumption to have his picture taken with Newt Gingrich -- in Hollywood!
You're right it didn't get "great reviews," nor did Russell's sci-fi flick "Stargate." But here in Los Angeles, while entertainment news said zip about Stargate, the movie was sold out at the matinees. Kurt Russell was extremely politically Incorrect.
And with Tombstone, here in L.A., the theaters were packed. We saw it twice at major theaters, and it had a very long run in the cheapo movie houses where matinees are a buck, so we saw it a third time there, in a rundown old standard issue 50s theater in Eagle Rock, a lot of juvenile delinquents with a good sprinkling of Angeleno-style Mexicans. It was the most fun audience -- they LOVED it, all those kids! The place was packed and it was as much fun as in the movie when the cowboys shot at the juggler! Just a hoot!!
Despite its many, many flaws and near invisibility to "serious" reviewers, Tombstone is one of the most beloved American westerns made.