George W. Bush left the White House as an unpopular president because hostilities in Iraq dragged on and on and our soldiers kept losing their lives to IEDs years after the Iraq army had been defeated.
If everything had been mopped up quickly, despite the lack of WMDs, Bush's popularity wouldn't have suffered as it did.
Obama is becoming more and more unpopular for different reasons. The economy is reaching historic lows and voters gradually understand that he isn't up to the job, which should have been clear to all before he was elected. Obama's ideas for improving things are misguided; he is a Socialist out of step with the vast majority of Americans.
More importantly, he killed a lot of people's dreams. They romanticized about him and vote for him based on those rosy reveries. Betray someone's dreams and you can expect retribution.
Many people who voted for Obama thought "no one could be worse than Bush." They know better by now, don't they? They miss Bush, not because Bush was a great president but because he was better than Obama.
Given the above, the billboard near Wyoming, Minnesota makes sense only as an indictment of Obama. If the country were traveling in the right direction and if Obama was hugely popular, then the billboard would rightly be viewed as an indictment of Bush (but why anyway at this point in time?).
The election of 2008 represented a breakdown of the entire process. Obama, unqualified and far too liberal, had no business being nominated by the Democrats. And John McCain was not even close to being the most desired candidate on the Republican side. Two mistakes vying for the most powerful office in the land.
The voters didn't do their job. The reason Congress has the lowest approval rating in history and the reason incompetent leaders rule over us is because the voters are incompetent as well. No one wants to talk about the role voters play in all this, but the horrific results of every election are their fault.
What we really "miss" are good citizens doing their job and electing quality politicians. We aren't there yet, "miles to go before we sleep." Change the system? Voter education? This won't be solved anytime soon. Enjoy the ride.
Update: As I said above, the billboard is pro-Bush. It's a conservative t-shirt.