The problem with that conclusion is that it, at least in part, confuses cause and effect, a well-known logical fallacy. Approval ratings for both presidents were and are very polarized, but are the ratings a reflection of presidential performance or a case of polarization being in the eye of the beholder?
The DW-Nominate chart illustrates the relative liberal/conservative ratings of all the presidents since Harry Truman. The same measures are used here as in Radical Republicans where they demonstrated the extraordinary and historically extreme conservative nature of Republican controlled House sessions since the mid-1990's.
The takeaway from the chart is that 'socialist' President Obama is actually the least liberal Democratic President in modern times and Bush the most conservative Republican. While Bush may have earned partial credit for polarizing Americans, Obama has not.
In Polarized Opinion Panderbear discussed how cable news networks target particular opinion demographics enabling viewers to immerse themselves in news with a message tailored to their biases. If you must assign culpability for polarizing the electorate, Fox News is as good a starting place as any. Also, as shown in Hypocrisy Belt, racism remains a polarizing factor in American politics. Sadly, Panderbear has observed the latter phenomenon first hand.