1. Virtually everyone who saw the intelligence believed Saddam had WMD, therefore Bush is being unfaily singled out for criticism.
The typical framing is: "Democrats got the same intelligence and reached the same conclusion, so blaming Bush for misleading America is purely political." The argument is also presented in 'gotcha' form by people like Sean Hannity, who use a lengthy blind quote about the threat posed by Saddam that turns out to be from Bill Clinton, John Kerry or some other Democrat. The conclusion is that if Bush was lying, they must have been lying too.
There is a false assumption underlying this argument, namely that Dems received the same intel as Bush (they didn't), but setting that aside, here are two reasons why this is a straw man:
a) The issue is not whether people believed Saddam had WMD (many did), or whether there was any evidence that he had WMD (there was), it's the fact that Bush and his administration made an absolute, unconditional case with the evidence at hand, brooking no dissent and dismissing doubters inside and outside the government as cowardly or treasonous. That's what "manipulating the intelligence" and "misleading the public" refers to, the knowing exaggeration of the case for war (whether by cherry-picking intel or using defunct intel or by speaking about ambiguous intel in alarming absolutes). As I wrote in this post: "There we were, more than a decade after the first gulf war, two years after 9/11, and Saddam hadn’t attacked us, he hadn’t threatened to attack us. And then suddenly, he was the biggest threat to America. A threat that required a massive invasion. A bigger threat than Saudi Arabia, North Korea, Iran, Bin Laden. A HUGE, IMMEDIATE threat. It simply defied belief."
b) In addition to the fear-mongering described above, the contention that Bush 'misled' the public is not simply about Saddam's WMD, but about the way the administration stormed ahead with their plans and invaded Iraq in the way they did, at the time they did, with the Pollyannaish visions they fed the world, all the while demonizing dissent and smearing their critics.
In both (a) and (b), the crux of the issue is proportionality. Whether or not Bill Clinton or France or the U.N. believed Saddam was a threat, the administration's apocalyptic words and drastic actions (preemptively invading a sovereign nation) were decidedly out of proportion to the level and immediacy of the threat. THAT is the issue.
2. After 9/11, we can't wait for the threat to materialize before taking action.
This is often used as a counterpoint to the notion that Bush overhyped the rationale for war. It's a vacuous argument whose logic implies we should invade a half-dozen African countries as well as North Korea, China, Iran, and Saudi Arabia. Every day that goes by that Bush allows these threats to "materialize," he is failing in his duties to protect the American public and should be impeached. And if the pushback is that North Korea and others are being dealt with diplomatically, isn't that exactly the approach this argument purports to refute?
Furthermore, the war's opponents never claimed they'd prefer to "wait" for threats to materialize. This is another straw man. Nobody wants to wait for threats to materialize; they just want to deal with them differently.