The first Bush Simpsons episode was amazing. Hellllllllllllo Mr. Bush!
I think the passionate HATRED is probably relatively equal between Bush and Obama. Note relatively, as you had a 9+ year build up of it for Bush, you have had a 1+ year thus far really for Obama. You also have 9+ years of Memories for Bush compared to the 1 or 2 for Obama.
I also think Redress hit a point with the "jokability" of a particular President. Bush I was relatlively bland and while Dana Carvey did a fun impression, beyond that there wasn't much. He didn't give a lot of great stand up fodder, he wasn't a big character, and he was over shadowed by the wonder that was Quayle.
Clinton as an impersonation was rather boring and didn't have a lot of good joke material for the majority of his Presidency. Oh hey, he's fat and likes hamburgers! hahaha. Seriously, Will Ferrel on MadTV's Clinton was abysmal and just not that funny. It wasn't until the Monica stuff happened that you started having a really great thing to go off of, and even at that point it gave better fodder for Stand Up then it did for parody.
Bush was just custom made for jokes and parody. He was extremely folksy, which was part of his appeal for some but also is ripe for jokes. His misspeaks were not just "wow that's dumb", or "eh, he said the word wrong", or "ah that happens once in a while"...they were often and often times hillarious on their own. Seriously, I don't see how anyone that's just looking at it objectively can't laugh at the notion of OB-GYN's not able to practice their love with women? Honestly, its just great. He was also an extremely animated individual, the type that talks with his body, his hands, his eyes as much as with his words.
A lot of those things made Bush endearing to some. I've always felt that he was a rather horrible speech reader but an above average casual speaker honestly. The folkys cadance and accent, the natural and unrefined body language, the slip ups to me added to the fact that when he was talking off the cuff and off script he came off as unusually honest and sincere for a politician and far more charismatic then he was when he's on a campaign stop or on TV giving a speech. But they were also perfect characteristics to launch into jokes. It also helped that almost immedietely you had Will Ferrel pull off a picture perfect Bush that remains funny to this day and basically gave everyone a blue print.
Additionally I think in part it was the age we were going into at that point too. It used to be all you saw of stand ups other than their show was if he was on a late show or HBO. Now you got Comedy Central having multiple stand up specials, youtube video of tons of stand ups, radio stations dedicated to stand up, etc. You have youtube, flash animation, blogs, and podcasts giving individuals tons of ways to proliferate their own comedy. All of which really started coming in big in the new decade.
Obama just isn't as ready made for comedy and, to be honest, comedy isn't as prevelant on the right. Not like its commonly thought of. Comedians are generally left leaning or libertarian leaning based simply on the life style that it generally gravitates to that kind of thing. Ditto for many comedy writers. That doesn't mean there's not right leaning jokes that come out, but I think its naturally you'll see a bit more about those on the right than on the left based even on the subconsious of these types of people.
Though seriously, there's only one option for the best and most fair Political satire out there today...