Write an apology
An apology is a formal justification or defense of a position.
His transitions from subgenre to subgenre in the 1970s was very seamless and flawless.
He's seen as one of the most important musical artists ever to come out of England, and that's what he is. So, about right.
He's definately had a dive in quality from 1983 onward (Heathen notwithstanding), but that doesn't mean much for someone as powerful as Bowie. His influence is undeniable in the creation of modern pop, everything he does, he does in a signature style that's been mimicked and never imitated. He can be both avant-garde and catchy at the same time, not to mention his staying power. This guy managed to take career-killing risks every few years and come back stronger than ever each time. How can you not at least respect that?