The lack of truly capable big men out there is an age-old problem. The dominant, versatile ones almost always go at the top of the draft. The ones drafted later usually have some limiting factor, such as lack of athleticism or no basketball IQ whatsoever or injury risk due to humans that size not being able to run up and down the court for 82 games.
So the question is do you just settle for one of those OK but flawed big men and pay them big bucks since there's such a shortage? Usually you can get by if they are lacking offensive skills but are great at D, rebounding, and picking up garbage points around the basket. Generally if you settle for the slower, good at offense type but horrible at D there is a limit to how good your team can be, especially since they command 10+ million a year just for the fact that they are tall and score a little.