I mean, it should be an issue. But we are a nation of dumbs, unfortunately.
Yes I'm sure Abraham Lincoln and Harry Truman were absolutely unfit to be President, unlike such eminently qualified college educated men such as James Buchanan and Herbert Hoover.
College education is a standard today and it wasn't in the past. Can't really compare. There are great men in history who were illiterate or only had 8th grade education. That is not fit for leadership in the 21st century.
Having a college degree was pretty standard for politicians and the like by 1945 and even in 1860. Do you think Scott Walker would be exponentially for qualified for leadership solely by virtue of having done a little coursework to receive his diploma? Is Lula of Brazil who ended formal education at second-grade a far worse leader of his country than Goodluck Jonathan of Nigeria who has PhD?
No I don't think it affects his ability to President. I think his resume as Governor of Wisconsin would speak to that question. It's also true nobody called W. Bush smart for graduating from Yale.
I think he can be attacked on it though, not as a personality flaw, but on education issues it definitely can be brought up.