As time goes by, we need angel investments for fewer and fewer startups. The cost more often is within the reach of founders own (or parent's and friend's) pockets. People like me need business savvy advisers more than money. Investors who bring only money to the table get less useful every year.
I think the bit you are missing about business advice is that what constitutes good advice varies a lot based on the size and ownership structure of a company.
If you are a 2 man bootstrapped company and you take advice from someone running a fortune-500 corp, you are probably getting horrible advice.
Really, if you don't need investor money, you are probably too small to benefit from most investor advice.
Still for most startups - though outside the realm of this board - cleantech, life sciences, and enterprise hardware startups still require major VC and PE backing over their life cycle.
For example - Better Place - a provider of Electric Car Service Stations just raised a $350 MM Series B with HSBC as the lead investor. HSBC doesn't bring management expertise - but they did bring $150 MM of investor dollars.
