The reason pharmacists can't prescribe medication is because they don't understand how to use it. They understand interactions and can save you from prescribing lethal combinations of medicines, but they don't have the background or experience necessary to practice the art of medicine.
There's a good reason for extended release low-dose Minocycline. Low blood levels of Minocycline have anti-inflammatory properties rather than anti-bacterial properties, and inflammation is the key target in certain derm conditions. Lower extended release doses increase tolerance and compliance. The sub-anti-bacterial doses in minocycline also decrease the risk of inducing bacterial resistance.
There -- you have numerous good reasons to write for a brand name if a patient has insurance.