LA Times reporter (and former Laura Bush press secretary) Andrew Malcolm:

President Obama today signed a document countermanding some documents signed by his predecessor and saying he won't sign so many other documents like that called signing documents.
...
Bill Clinton actually used signing documents way more than George W. Bush. But No. 42 is a Democrat and his wife currently works for Obama. So No. 44 is on a big tear right now to distance himself instead from No. 43, the Republican, who's back in Texas and doesn't care but just hearing his name trashed makes Democrats feel good.

Oh, really? That's why people have focused on Bush's signing statements? Or could it be that Bush's signing statements have been substantively different from Clinton's? Here's what a September 2007 Congressional Research Service report has to say:

At first glance, it does not appear that President Bush has departed significantly from prior practice in the signing statement context, having issued 152 signing statements as compared to 381 during the Clinton Administration. However, the qualitative difference in the Bush II approach becomes apparent when considering the number of individual challenges or objections to statutory provisions that are contained in these statements. Of President Bush's 152 signing statements, 118 (78%) contain some type of constitutional challenge or objection, as compared to 70 (18%) during the Clinton Administration.37 Even more significant, however, is the fact that these 118 signing statements are typified by multiple constitutional and statutory objections, containing challenges to more than 1,000 distinct provisions of law.38

UPDATE: Steve Benen adds:

Did Clinton use signing statements “way more than George W. Bush”? It's a highly misleading claim, based on a count of the individual documents, instead of the number of provisions to which the signing statements have been applied. In reality, Bush "broke all records" while abusing this presidential tool, “using signing statements to challenge about 1,200 sections of bills over his eight years in office, about twice the number challenged by all previous presidents combined.”