That's largely because alternatives like Postgres exist. If they didn't then I'm pretty sure the the conversation would be more along the lines of "take it or leave it."
People shouldn't underestimate the commoditization of databases that has occurred since MySQL and Postgres became acceptable alternatives.
Has nothing at all to do with Postgres, or underestimating anything. Microsoft has a very large, robust partner network that's able get great pricing and the cost of MSSQL really hasn't changed much over the years outside multi-core updates.
People shouldn't underestimate the commoditization of databases that has occurred since MySQL and Postgres became acceptable alternatives.