Asking for free art does seem rather bogus.

It's about at the same level as non-technical people asking for free IT or code.   Code *is* art. 

I had answered this craigslist ad a long time ago for someone looking for a Google Apps/Domain expert. I was interested. It turned out to be a fairly neat small food services company.   They had some good marketing and high end catering trucks was a trend.  I did some configuration and work for them, but ended up getting screwed over what really was pennies in my free time.   They still call me from time to time, and I am completely appalled.  If they paid me the couple hundred they owed me and gave me some outrageous hourly rate rounded up to 100 hours with that amount pre-entered into escrow, I might consider it.  

The last time was because they had to spend "3 hours" on the phone talking to Google support and they might have to pay them for support and for business seats past their "free" level of signup.  They were so appalled that they might have to pay for support, that they promised the moon to me.  I asked them if they were too cheap to pay for the modest Google support, why on earth would I think that they would pay me when I cost 10x as much?  You'd think they'd figure it out, but they kept calling for at least a week. 

But the more serious question is, why would they expect free, expert IT work?

Great question. Free is usually worth less than what they pay for it.

I've never really understood why they think THEIR exposure would be better than doing it on your own terms. A gallery show, a con booth, or even a DeviantArt account are probably better exposure for an artist than what they could offer. Friends are the only thing that I could see getting an exception... at least they'll probably buy you dinner.

It takes an arrogant confidence to believe that they could get more distribution than deviantART.