"Entourage" seldom veers beyond pleasant

Usually, when I watch a show every week, it's because I enjoy that show. Perhaps I like the writing and/or the acting. Maybe I'm attached to the characters or find the stories addictive. At any rate, there's something that brings me back every week. Then there's the handful of shows I seemingly watch for no reason, other than habit. Maybe I once found them compelling, but, now, they are hit or miss at best.
In the past few seasons, HBO's "Entourage" has become one of those shows. Once a fresh, funny portrait of the life of a movie star and his various hangers on, the show -- which returns for its fifth season Sunday at 10:30 p.m. -- has become a bit tired, with nearly every season subscribing to the same formula: Movie star Vince (Adrian Grenier) is on the cusp of getting a big movie. He doesn't get it. It looks like his career is in jeopardy. Then, at the last minute, he gets either that movie or another, better movie. End of season.
Vince and the supporting characters have grown and evolved little over the various seasons, with Drama (Kevin Dillon) still a clueless pain in the butt, Turtle (Jerry Ferrara) still a goofy mooch and Eric (Kevin Connolly) still a loyal but wussy buddy/manager seemingly incapable of wresting himself from Vince's side.
Judging from the two episodes sent to press, the show does seem to making some movement toward changing the characters a little. Vince, it seems, is on a career upswing (and, in magical "Entourage"-land, does a guest spot on the "Tonight" show -- which is still hosted by Jay Leno!). Eric is planning to move out and is circling his flirty but hesitant ex Sloan. And Turtle, inexplicably, is still dating Jamie-Lynn Sigler (playing herself).
But these changes are too little too late and, as usual, whatever juice the show has comes from the character of Vince's agent Ari (Jeremy Piven, seemingly recovered from his bout with mercury poisoning)
Like the other characters, Ari is still pretty much the same guy he always was: loud, abrasive, occasionally cruel. But if the character is static, at least he's interesting, particularly in his interactions with his smart, ambitious assistant Lloyd (Rex Lee, who, unlike the show around him, is NEVER not funny). This season, Lloyd is trying to move up in the ranks, from assistant to agent, and Ari is struggling with both that and his new partnership with his friend Andrew (Gary Cole).
The scenes with Ari barking at his minions, and sweating over keeping it all together always make me wish that this show was about Ari and not Vince.
But it is about Vince. And, as such, it's not exactly bad -- just unremarkable. It's a pleasant enough way to spend a half hour a week, and, chances are, I'll keep doing just that.
But why?
The new season of "Entourage" premieres Sunday at 10:30 p.m. on HBO.