I could be mistaken but in my case I never forced anyone to use their artistic skills, it was actually more often voluntary from them.
Basically everyone was doing their part using their skills if they had some useful for the project, or just their time/sweat.
The relationship we had (still have, actually) was healthy enough so they could just tell us to piss off if they didn't want to do it. I particularly remember one such instance, because I ended up doing an ugly poster but when asked, I said it was the work of our skilled friend.
On the other hand I've been spending at least an hour per week doing sysadmin work for various groups/clubs, it's not the funniest thing in the world, particularly in the evening when I already spent the whole day doing it at work, but it's just me doing my part for the greater good!