I think the first important thing to say is to appreciate his talent and legacy. Also that people are free to look whichever way they want, it's their life and this signature look is for his music scene. But from an aesthetic POV, he looks total crap. I mean he was never a good looking guy but staying like that in your what 60s, people would lol at him behind his back without his status.
The fake black hair just makes his skin look even older, paler and wrinkled, he's even dyed his eyebrows! The vertical face, probably 8-9cm forehead, long hair just add to a peculiar look. At that age most people should incorporate some greys, I mean he should have been doing it a couple of decades ago the way he aged. Bit of grey, shorter hair and a beard, he would look at least normal. Beards are cool but as a younger guy if you're handsome you can shave or keep it as either way you look good and fresh skin wise. Though the beard will add points due to the trend. As an old guy a beard on the other hand is essential, it will help retain some facial structure when the skin has turned bad. Oh and I think he has had a transplant, just it looks receded and weird due to his forehead and not particularly well placed grafts. If he was a masculine looking middle aged man like Frank Grillo with better skin and a tan, he could get away with dyeing it for sure. But even he is now reaching the point to change his look a little and that's normal even for the best as you get towards 60!
I'd still say a hairline transplant is worth it for a guy with normal dimensions. As you age, many people will have combovers at the front or expose hair loss at the hairline - both destroy looks. A nice, symmetrical hairline does wonders for styling.