In today's tough economic climate, it has never been more important to be employable, and Hogwarts has failed its students in this.
The Dursleys had the right idea. While Dudley is climbing the corporate ladder, Harry Potter will be collecting his unemployment...
1) Hogwarts has a complete disregard for academic excellence, leaving students with no formal qualifications.
2) Scarred by their Herbology lessons, wizards have a habit of attacking pot plants, which does not look good in job interviews.
3) Illiteracy is rife in the Wizarding community.
4) Being used to instant teleportation, wizards would quickly become enraged with commuter traffic and stab someone.
5) Without dragons, quidditch and mortal peril, wizards would soon become despondent with the 9 to 5 life.
6) The celebrity culture within Hogwarts breeds a sense of entitlement.
7) The level of eccentricity at Hogwarts means most students could never truly integrate into modern society.
8) Magical folk age well, if a little unconvincingly, meaning they would suffer the jealousy of their sexual competition.
9) The Hogwartian idea of 'formal dress' leads to confusion in non-magical smart-casual occasions.
10) An inbred aversion to speaking the name of fearsome despots means that Wizards cannot communicate with corporate authority figures.
Wizards and Witches, in summary, are completely unemployable in the Muggle world. Segregation may have caused problems in Muggle society, but magical follk have a long way to go before full integration is on the table.