I think what most people have a problem with fractal art is that composition wise it is often very samey, and colour wise it often very garish and unsubtle. A few of these are nice - I still really like Space Station, but a lot of them just look like ugly blankets from Glastonbury Festival.
Your comparison to photography is almost fair enough, but photography often works with narrative and objects familiar to the human mind to create different emotions and raise different questions.
It's good you sold some, though. It does look nice sometimes and I know some people really love it.