In the example I used earlier, a tropical storm may be incredibly beautiful and aesthetically pleasing, but it is not art because it does not exist for the purposes of an audience having a response to it. It exists because of physics. If I had the ability to cause a tropical storm, and it did it for the purpose of causing an emotional reaction, the methods I use to create it would be called art, and the storm itself would be a work of art. If I accidentally drop paint down the stairs because whoops, it's not art. If I throw paint down the stairs in hopes the (seemingly) random ways the paint spills will turn out to be beautiful to me or someone else, I am making art. Art requires the intent to provoke an emotional reaction, even one as simple as joy. Even something as simple as carpentry; if I'm making a step for my front door in order to decrease the strain on my legs, it can be said I'm doing it to receive a positive emotional reaction (happiness caused by realizing I've reduced physical stress). In this case, I have made a work of art, however shallow it may be. Art was the process by which I determined the reaction I wanted, determined what actions I could perform to provoke the reaction, and then performed them. Conversely, if I hated someone and intentionally made their step shitty so that they'll have a bad time with it, I have also made a work of art! I wanted them to be angry at the step's functional failure, so I determined what I would have to do to make the work provoke that reaction.
In your example, you used a piece of Jesus Toast. Jesus Toast is not art because various physical reactions occured to burn the bread in the pattern of a bearded brunette man, it is merely just a result of heat being applied to bread. But if you sought to provoke an emotional response, toasted the bread in a way you believe would engender that outcome, and then made an observation on it, now you have created a (shallow) work of art. If you just threw bread in there in order to apply heat to bread, then no. If you threw the bread in there in a way that you believe will toast it the way you like it toasted, now you can be said to be making art, with you as the sole audience and joy as the intended reaction.
To crib one of your examples: if you drop paint down the stairs & the stairs' owner demands you leave it because he thinks the splotches look beautiful, is it art? If so, who created it: you or the owner? Related to that: if someone takes a photograph of a natural storm, is it art?
My main point still stands with your argument, though: the basic question here is about emotions & motivations, not acclaimed artwork. Under your definition of art, the AI would still need self-motivation and empathy to even create it. The art itself is moot; the reason for doing it is important.
Personally I don't believe it. Because it would be needed sensibility, the capacity to feel and being struck by a stimuli. The essence of living. And even harder would be to try and encompass the gap between a human and a cyber sensibility.
I think you're assuming all art is good. Everyone has an opinion of what art is. Any crap can be declared 'art'.