I've got 3 of the little suckers with 16GB of RAM and SSDs and just opening a 3D program gets their little fans sounding like 737s ready for takeoff. The video is clearly the weak link, and My MacPros are a much better solution, even the old 8-core.
I do agree that most people are fine with a mini, but whenever I suggest them to people with appropriate needs they usually turn their noses up at them. There seems to be no shortage of people buying nMPs to check their mail on.
As for your photographer friend, Monitor choice is important, and I salute him/her, iMac screens are not suitable for high-end photography. The Holy Grail is the Mid-range Headless Mac, but Apple will never give it to us, so Minis will have to do unless you feel like buying "The Tube".