If designing anything to be fastened to racks etc (maybe not so much for bar bags), remember that it will get covered in oily water from the road, or mud if any tracks etc are involved.
Therefore any design that involves pale colours -whether part of the design or part of the background - will very soon look very grubby unless it is made of scrub-able material - and even then most cyclists wouldn't bother (clean the chain, yes, clean the luggage, less likely).
You will never get the perfect bag for the majority of users - you only have to look at all the different sections on this forum (if you have bothered) - people do a lot of different things with their bikes, and the luggage needs vary with use.