If there is a great achievement in modernism, then it is the realisation that it is better to present things straightforwardly, simple and clearly. That window dressing, ornament and unneeded complication are great enemies for the effective transfer of any kind of information.
Within art such clarification efforts first lead to geometric abstraction such as the works of Piet Mondriaan, which was consequently further refined and eventually ended up at the austere forms of what is commonly known as minimalism. As this formalist direction was somewhat of a cul-de-sac, attention quickly shifted elsewhere.
The viewpoint that art and art's materials should be art's only subject matter was abandoned, although the post-modernist works that followed very much maintained that modernist adhesion to clarity. In his works Jean-Michel Basquiat uses various materials, many contrasting colours and little in the way of easily describable geometric shapes. Yet he brings it all together in a clearly legible overall ensemble, just one that consists of many more parts. The same goes for artists like Jenny Holzer, Felix Gonzales-Torres, Sherri Levine, Sarah Lucas, Juan Munoz, Pipilotti Rist and so forth. Their works are perhaps difficult to interpret, but they're very easy to read visually. There is little, if anything, added to those works that doesn't serve a specific function and the elements that are present are distinctive, both within the boundaries of the work and in regard to other works and objects.
This 'as simple as possible, but not simpler' principle can still be found in the more recent trends of installation art with complex narratives, such as the work of Simon Starling and Sarah Sze. It is thus the great enduring strength of simple and clear expression that it communicates as effectively as one possibly could. Whatever it is you wish to draw attention to, it is always and forever achieved best by removing unnecessary elements and working hard to find 'le mot juste'.
Outside of art, especially so at the turn of the millennium, I believe that this kind of simple and clear expression has had largely negative connotations with commercialism and politics. Clear-cut unambiguous visual communication was and is linked to corporate logos, political slogans and other easily-digestible formulaic arrangements. Naomi Klein's aptly titled book No Logo is a clear example of this sentiment.
This association presents a problem for those who wish to simplify and clarify, as their efforts can quickly be conflated with reductionism. Reductionist thought is almost always harmful because it is produces incomplete and thus incorrect points of view.
Moving back into art, it is easy to notice that in the last twenty-odd years there has been a shift away from readily understandable and coherent visual structures. This shift could be understood, and would even be justified, if one imagines that art's subject matter has become ever more intricate and complex, so that analogously these subjects could only be treated in the most arduous of ways and through the most complex of forms.
Yet what we see is that the subjects that are being dealt with are increasingly reductionist views about binary relationships; rich vs. poor, men vs. women, black vs. white, and so on. Those reductionist messages are then propped up by adornment and ornamentation, which serves as an overall detraction of both. If a message is too rudimentary to be spoken about in anything other than one-dimensional symbols, then dressing it up in shiny packaging diminishes it even further by increasing the distance to the information.
Ultimately the most important skill an artist can have is the ability to present things as clearly and as legible as possible. If you can do that, you can make art out of any material and about any subject. If you can't do that, then you're simply speaking not a very good artist.
Artists who never achieve great clarity have however always had their own place in history and thus the issue with this trend at the present time doesn't lie with them. Instead the predicament comes out of a critical reception that is putting greater emphasis on the subjects these works discuss rather than the lack of clarity and convoluted presentations with which they do so. While nobody denies that certain issues are of great concern to the world, what is being said in an artwork is less important to it's 'art' than how it is said. If the present concern for subject matter and personas in art is thus taken seriously for too long, then one runs the risk of art becoming nothing but beautification of life's minor and major inconveniences.