I think you'd have to define "commercialising", because even the greatest and most sublime artistic works were created professionally. Mahler for example, did not write symphonies, nor did Michaelangelo paint great religiously-themed murals, just for the love of doing so. Whilst that was certainly their drive, they were not altruists. They worked as artists for a living; and many of the great composers of the past were also music teachers and managers as paid employees of their Church or nobility patrons.
I think art is cheapened if high-jacked for shallow commercial ends like supermarket "Muzak" and backgrounds to advertisements for ordinary commodities; or misappropriated by the lazy or inept to avoid being creative themselves. Art does not need to be of great depth to be so cheapened: even the best pop music is hardly on a technical or emotional par with a major symphony, concerto or chorale, but it is still diminished if "sampled" and thrown together with a synthetic beat in an afternoon on a computer by some DJ unable to write anything worthwhile himself.
Even at a slightly higher level, I accuse the Disney Corporation of diminishing and cheapening others' work or folk-culture. As far as I know, Mickey Mouse and Fantasia - perhaps also Bambi? - were among the very few things Disney's writers ever actually created originally. Everything else of their better-known output is degraded versions of children's stories by (mainly) British and European authors, and European folk-stories, plus I think one or two by Americans; re-worked and made to appear as if entirely Disney's own inventions.
On the other hand, perhaps "Art" diminishes itself at times. When some supposed "Artist" a decade or so back exhibited a stack of bricks as "art", and when Tracey Emin showed her "Un-made Bed", both they and the high-falutin' of the Art World generally were derided right, left and centre by the public who don't share the modern-art world's lofty disdain for anyone expecting to see a clear display of skill irrespective of style. The latter is obviously always a matter of personal taste anyway - I am not a ballet fan but I have the greatest respect for the dancers' abilities.
The average non-artist is not stupid; and probably knows there is nothing new in new styles in any of the arts being rubbished by contemporary critics of excessively-conservative tastes. He or she has no problems admiring an Impressionist painting or a highly-stylised statue (e.g. by Barbara Hepworth). Firstly, such styles are now generally respected, and secondly, their subjects, messages and evidence of skill are usually clear.
However, Mr. or Mrs. Average-non-Artist has little patience with the likes of the critic Brian Sewell lauding some of the stuff shown at the Tate Modern or in similar "spaces" (must get the jargon right). The main difficulty with such material arises when it commands silly praise and prices for what appears a cynical refusal to use any genuine creativity or technical skill. Anyone can stack house-bricks neatly or make a bed untidy, but if some Name can command absurd fees and high praise in the right Sunday supplements for doing just that, then where is the art?
Or is this diminishing art to purely commercial exploitation of those with more money than sense, by those accustomed to earning money for little obvious talent?
