I'd be really sad if Artie left. I was waiting to see if he'd be in the next day after each day he turned out now to be in, and every time Howard said he wasn't back I got a little bummed and enjoyed the show less.
I can understand the Artie haters or the people that can't care either way if he's on the show, but I feel like he rounds out the cast of characters. It may just be an act but Artie is that "everyman" he makes good scratch but it doesn't help him with his personal issues and he doesn't try to make himself seem better than he is because he has money. He does all those charities for unfortunate people and you can hear it in his voice when he can identify other people's classy moves as he genuinely seems to understand right and wrong moves. He just falls victim to some mental issues in his personal life.
Most, if not all of Artie's stories (on the show at least, I never saw him live) make me crack up. It's in the way he can set up and tell a story. The coke-pig MadTV story clinched it for me when I got back into listening to Stern a couple years back.
I hope he's alright and maybe he just has the swine flu or another bad flu. I really want to feel like that's it and he'll be back in a day and really laugh it off that people thought he was gone. But if his self esteem and confidence is low because of his father/birthday thing, being doubted by everyone is not going to help.