Nevertheless, the quadrennial conventions retain their privileged place on the nation's political calendar. Even as broadcast networks scale back their coverage, both parties will spend millions to stage them, 15,000 credentialed members of the media will show up, and cable channels will give them wall-to-wall coverage.
Why? Because people still watch.
After a decades-long slide in ratings, the share of households watching the conventions rebounded in 2008. In fact, partly because there are more television households than ever before, the average total audience in 2008 was the largest ever.
About two-thirds of Americans watched at least some part of the 2008 conventions, according to the Nielsen Co., and ratings peaked during the presidential nominees' acceptance speeches. The numbers rival the other major quadrennial television event: the Olympics.
Half the 2008 audience watched both conventions.
"It really is a nonsense argument to say no one watches the conventions," said Jill Edy, a University of Oklahomaprofessor who studies the numbers.
"People who are politically interested already - for them, this is appointment television," she said. Those people usually watch on cable.
There's also a chance to catch some of the hardest-to-reach voters: independents who might be channel-surfing Thursday night and stumble upon the acceptance speech airing on all the major networks.
Since 1972, when the modern made-for-television convention first emerged at the Democratic and Republican conventions in South Florida, 10% to 29% of voters have said they make up their minds during the conventions, according to the American National Election Study conducted by Stanford University and theUniversity of Michigan.
Conventions no longer do what they were designed to do: decide a party's presidential candidate. That's determined in a much more democratic series of primaries and caucuses.
Modern conventions are week-long scripted "infomercials" for political parties, where every moment is carefully choreographed to avoid controversy or gaffes.
"You can't think about the last time you went to a convention and wondered what would happen. You don't even wonder if there will be a rules fight or a credentials fight or even a platform fight," said Byron Shafer, a University of Wisconsin professor. "The convention is objectively less important."
The nomination itself is legally necessary.
A party candidate's name cannot appear on state ballots until he or she officially accepts the nomination, and the candidate can't spend campaign money earmarked for the general election until then, either.
The convention itself could, theoretically, be canceled in an emergency. GOP rules have a contingency that would let the 168-member Republican National Committee nominate Romney through another mechanism in the event the convention "cannot convene or is unable to conduct its business."
Canceling the convention was never an option, GOP officials said this weekend.
One reason: The nominee's acceptance speech on the closing night -Mitt Romney will deliver it Thursday as usual - may be the longest unfiltered expression of who the candidate is and what he stands for that most voters hear all year.
For better or worse, it can provide some of the most memorable lines in American politics.
Think of Franklin Roosevelt's "New Deal for the American people" in 1932, Barry Goldwater's "extremism in defense of liberty" in 1964, George H.W. Bush's "thousand points of light" (and "read my lips") in 1988, Bill Clinton's "bridge to the 21st century" in 1996 and John Kerry's "reporting for duty" in 2004.
"There are really very few national political moments where we convene and commune with those national leaders without being filtered by some commentator or someone telling us what we ought to hear," said Don Baer, a former White House communication director who wrote Clinton's 1996 speech.
Clinton was famous for giving long-winded speeches, but Baer notes that the ratings for Clinton's 79-minute acceptance speech in 1996 actually went up as it went on.
"People actually crave this. They yearn for that ability to convene directly, without filters, with their national leaders," Baer said.
Beyond television, the delegates - a few thousand party leaders from all over the country - use the convention to plot strategy, decide platforms and determine internal rules. They do so in a focused, energetic environment.
"In an age when many things drive the party apparatus apart, a party convention brings the party together," said William Harris, CEO of the GOP convention. "If you believe as I do - that the two-party system has brought strength and stability to our political process - this is a part of that process that needs to endure."