Once upon a time, artists were only respected as such if they were masters of their tools and materials, and produced paintings and sculpture which were well crafted. Artistic masters were the cream of the crop in terms of technical skill and ability, and they passed their knowledge and skill on to the next generation which made improvements that were passed on and so on. This explains why the quality of artwork improved over time from that of Giotto's work to that of Bouguereau's (a bit of logic that Hockney is apparently unable to grasp). In this way, mastery was relative to the progression of time, and it was considered apparent, as anyone from a 9 year old to a 99 year old could easily recognize the level of skill that went into a work of art. That is still the case to a large extent. However the traditional mastery role of the artist has been superceded, according to most modern books and art critics, as a new emphasis has been placed upon the value of artwork.
What is this new emphasis? To put it plainly, the emphasis is on innovation. But unlike the sort of innovation which obviously improved and varied the work of traditional artists over time, this new sort of innovation is a bit more ambiguous. And it seems that many of the supposed innovations of modernism aren't quite as innovative as is generally assumed. Even the appointed god of art (I didn't get to vote), Pablo Picasso, admitted this when he saw that cavemen had been producing "modern" art 20-some-odd thousand years ago ("so easy a caveman could do it"...haha).
If it appears that I have pure disdain for the new role of artists (which I will further define), then I've mislead you. What I have disdain for is the occasional abusal of this new role and the dishonesty (or perhaps delusion) that is employed to raise what amounts to a finger painting above the status of works produced by highly trained artists. This is not progress; quite the opposite. I wouldn't be surprised to learn of some new avant garde artist who "paints" with air onto air to "innovatively" express his air-headedness. Nor would I be surprised to see an entire 300 page book written on the brilliance and significance of his "work," or an empty 3000 square foot gallery exhibiting his invisible "masterpiece."
It isn't all B.S., though. And I have to admit that placing boundaries on art is as dangerous as removing all boundaries. That leads me to further define the new role of artists, which is to push the boundaries without falling into the B.S. abyss. And while it should be no crime to fall into that hole of hogwash, it shouldn't be applauded either. That of course is just my opinion. It seems that in the opinions of many, however, the new role of artists is to completely, without exception, abolish all boundaries on art. Perhaps I'm misinterpreting this but, at any rate, I reject that role.
It's important to consider why a new role emerged. The invention of the camera certainly played a part as it may have seemed to replace the need for traditional artists in some ways, though I'm not sure how a camera could create pictures of imaginary settings or exaggerated colors/values or any number of the things that artists had been doing for hundreds of years prior to its invention. Regardless, the ability of a machine to instantly create an image prompted artists to explore modes of visual expression that could not be challenged by that machine.
Furthermore, regarding painting, I believe that artists such as Bouguereau and several of his contemporaries had, quite frankly, hit the pinnacle of fine painting in terms of technical skill. I believe that this threatened artists who simply didn't have the capacity to compete with such incredible ability and so the only way to compete in the game was to change the rules and thus, create a new role for artists.
Truth be told, I'm glad the new role emerged (I just don't care for most of the people who claim to be the authorities of it). If it hadn't, we would never have been blessed with the likes of Salvador Dali or the plethora of amazing and exciting new artists that have emerged, though often without acclaim, in the past 30-something years. Sometimes you have to lose your mind to truly find it. I think the art-world lost its friggin mind for a bit and is now finding it in a truly new and sane way. In my opinion, the greatest art in all of history is being created right now by artists all over the world. I see it all the time via the internet and it's very exciting. Technical skill (human achievement!) seems to be popularly strived for again but it is tempered by the spirit of innovation given to us by some crazy fools who probably didn't fully realize what sort of seeds they were planting.