There must be a reason why The Artist isn't called The Actor or The Director. Is the title an homage to the artistry (and artists) of early cinema? A shout-out to the old trope of the tortured artist (which George definitely fits, with all his drinking, smoking and brooding)?
Although actors are often called artists, the word "artist" is a little different from the idea of actors as cattle or putty at the whim of the director. Like George says in a newspaper interview, "I'm not a puppet, I'm an artist."
An artist is a skilled practitioner. An artist creates.
In the battle between George and the movie industry, as embodied in fat cat Zimmer, there's more at stake than just his pride. George is fighting for an older concept of filmmaking, one grounded in artistry and tradition, rather than flashy new technologies and tons of cash.
Early film stars did their own stunts, worked long days, and often directed, wrote, and starred in their productions. They weren't afraid to get their hands dirty.
An artist makes something because they feel compelled to, and because they get joy from making it. Throughout the movie it's clear that Peppy and George are destined to be actors. Both of them really are made for the screen, and they're happiest on set. And there's a palpable joy at the end of The Artist—it really feels like what's being made isn't just entertainment, but art.