I was made aware of this issue by a Dental Hygienist.  As a lifelong customer of many different dentists, I know that the Hygienists are the ones who spend the most time with me.  I definitely prefer to have a Hygienist who has spent time and effort on their career rather than some random assistant who is probably younger and undedicated.  I have often been confused by the roles in the dentist's office - I am paying for the dentist to take care of me, but see the dentists less and less.  Whether or not this turns out the right way, I will vote with my $ and go to Dentists who care about me with good Hygienists.