Why isn't it in the top 250?

The number of votes. I think that the limit is 5000 or somethink like that.

There are a lot of movies with score higher than 8 who are not in top 250 because of numbers of votes.

Minimum 1300 votes needed. Plus its weighted average would probably be lower that 9.1

because its not good enough

When there's no more room in hell, The dead will walk the earth...