A lot of Wall Street firms hire more people straight out of undergrad than they do from MBA programs. The best way to get into Wall Street is to go to an elite school, get good grades and have enough of a personality to not get thrown out of interviews. Plenty of people do it post-MBA, but with work experience (some people worked in corporate America, others at consulting firms, really anything).
CFA has required work experience for at least a decade. Taking and passing the exams, however, shows a dedication to learn and also shows that you have a certain body of knowledge that is valuable in certain occupations. Plus you can put that you've passed the exams on your resume without having the CFA Charter as long as you do it in the manner prescribed by CFA Institute.