Do you think that you could create some interesting material within amiga's artistic applications if you were running a cutting edge one? Or is the system simply not made for these purposes?
Well, for fixed-resolution work (pixel art), it's still tough to beat DPaint or Brilliance on Amiga. They are really nice programs with some pixel-level features you just don't see in Photoshop. If I want a small, fixed-resolution character or design that I can fit in 256 colors, I still reach for my 1200 and Brilliance AGA.
I rarely use an Amiga for a full project, anymore, though. Photoshop has a lot of modern features that are nearly essential to my needs, which most/all programs on the Amiga are missing. (Savable file format that preserves working layers, text layers saved as text for easy re-editing, advanced layer effects, full history tree with history brush, all sorts of filters, file sizes and resolutions above chipram size, and the list goes on...)
I have no doubt on a sufficiently spec'd Amiga you CAN still produce great works... Just that it in many cases, it will take a LOT of effort to work around the shortcomings.