Descriptions of what differentiates 'wallpapers' from 'pics of Fido' and other 'art' have been made on several occasions.
The first [and possibly MOST significant] is that an individual's "ideal" desktop wallpaper will almost always be that 'picture of Fido', or some other family member....usually one who's equally cute, cuddly, and/or small.
THAT sort of 'wallpaper' ONLY appeals to its author - Fido will mean next to nothing to anyone outside his family.
Uploads of Fido are best sent to Deviantart under the quise of 'photographic mastery'.
Next issue is with WILDLY distracting graphics, either stark contrasts, patterns or absurdly bright white...all in themselves contributing to a potential for screen 'burn-in', but as equally an issue with eye-strain.
Third...overly CLUTTERED graphics making icon/gadget/Program placement and FINDING of them confusing and difficult.
Fourth... branding, tagging [over-use of text] - often as relevant to others as 'Fido'. Make signatures SUBTLE if you MUST have them.
Fifth...like Highlander....'there can be only one' - blue swirlie.....Digital Frost....Blue Mushrooms....Torus....floating spheres....twin moonrise over beach scene .... etc. If YOU have done it ONCE chances are others have, TOO before you...and better]. Don't do MORE of them, and no, blue-swirlie-with-pink-blob is not exciting, creative and innovative.
Lastly [in this short list]...once you've presumed your brilliantly original wallpaper will be lauded over by one and all [those who didn't see your equally original 10 uploads the day before] don't adopt the notion that this brilliance MUST be converted to every suitable format and loaded to THEIR galleries too.
I'm pretty sure I didn't want to see 'Fido' on my desktop...so it's a safe bet 'I' won't be wanting it on a Logon, Bootskin, OR Dock Icon.
Image 'creating' programs.
I am currently skinning within a Flight Sim called FSX. The graphics are pretty darn good in-game. I can press 'P' and pause a flight....change to external view [if not in it already], pan in 3D with the Joystick 'hat' and press 'PrintScreen' and have a squillion 'sexy walls'.... AS FAST AS I CAN CLICK A BUTTON or two and save.
One or two might be mildly diverting....choosing the ideal viewpoint might even require 'artistic talent' - an eye for composition, but at the end of the day it is no more than clicking a button and going "wow". Once the novelty is gone it's time to move on.
Image generators are almost always only 'novel' to their users. Most people have seen it all before.
The fractals...the 'alien' chrome spheres....the earthrise from the moon.