Imagine what SUN could have built, if they had $1 billion in cash to spent on a Database. Stupid managers wouldn't let them, but they spent $1 billion on a hyped DB with questionable quality.
I always thought of the MySQL purchase as a last desperate attempt to get their geek mojo back. Not something that they could have done with an in house solution (quickly).
It still didn't work, but I don't think they were just trying to buy a database.