I don't think it has much to do with his skin color. Most people who run for president have a strong background that give them something to base their governing style on. Obama is probably the first to run for president by building on the grass roots instead of based on their national reputation as a leader or prior national service in areas of government. Most people who have become presidents were governors.
It would be easier to understand him if he would say he wants to put America back the way it should be rather than all this talk about change. There is nothing to base what he means by change on because of him being so unknown and unsubstantiated on a national basis.
The changes he claims have been put out there before by Carter and McGovern. He gives the impression there is even more to it than that. It is something that worries some people in view of what has occured in this country in the last 8 years. Most people don't really want to change the country. They just want something that relates to normalcy again. In other word, the country hasn't really been normal for the last 8 years. I suppose a lot of young people just think the country has always been like this, but that isn't true.