The system you suggest would result in an affluence and social class divide. In order to ensure that only the most passionate and intellectually gifted reach University, harsh admission processes must be enacted - similar to those in place at Oxbridge. And, what do we have at Oxbridge? A class divide; and it does exist. Why? Why, because the private schools provide kids with a much fuller, and more respected education (IGCSEs, rather than GCSEs, for example); consequently making it much simpler for the richest to access the top universities, being better qualified. Allowing only to most qualified, and those that appear to be the most intellectual, to attend, is to make University for the rich, and mediacracy for the poor.
While it is true that this is an issue, there is no fair way to weed out the most intelligent. For example, an impoverished Michael Faraday was never allowed into any formal education, due to his simple inability to keep up with his privately educated, more affluent peers. Nonetheless, he discovered electromagnetism.
Your system is a replica of an older one, and would not only create a divide at Universities and, consequently, in society, but also result in us preventing the next Faraday from discovering the next E=mc^2.