I've gotten some flack for this, and I've seen NUMEROUS other artists get worse for it, so I thought I'd explain why this is a thing.
First, let me point out that I do occasionally gift art. It's usually not asked for, just a present from me for someone who I care about. My art is very
important to me, very personal, and every thing I create is like a little piece of my soul. I also, occasionally, host giveaways and contests for free commissions, but even then it's an incentive rather than just me going "yeah sure, I'll do this for free."
Art trades are okay with me too, as are collabs. I do like to do so lineart for a friend and let her color it. She's FAR better at coloring than I am anyways lol.
But, when it all comes down to it, art is what I go to school for. Art is my way of contributing to our income. I find it really rude for people to come up to me, "Hey can you do this thing for me for free?" I wouldn't walk into your place of business and ask you "Hey, why don't you hook me up?" Sometimes friends do, and I do, in turn hook them up as well. It's not something I expect though, considering giving away free shit at your job is a good way to get fired!
People act like the arts are trivial, and that we--as artists, writers, musicians, whatever--just magically poop out these works and that we don't deserve to get paid for it. For many of us, these things have been lifelong things we've worked on. Some have to pay their way through art school. Some are naturally gifted, but still spend years honing their style, their talent, ect.
So I don't just willy-nilly do free art for people, because this is my job and a way I'm able to spoil my kids with something extra when I'm getting commission work. Keep in mind, while normal jobs pay you by the hour on the regular, most artists are only paid via commission. Which means, if you aren't doing art, you're not getting paid.