If you shoot in an auto mode, you immediately lose the right to wear one of those cool, "I Shoot in M-mode" t-shirts. If you shoot in an auto mode, you also will not earn membership in the exclusive "Manual exposure is for accomplished shooters" society.
If you shoot in auto mode, you lose the option to embellish stories of your photo triumphs with this little gem, "So, as the __________ approached the ________, I was in manual mode, so I knew the shot would be friggin' perfect!"
As you can see, shooting in an auto mode can be very harmful. There is anecdotal evidence that shooting too much in auto mode might lead to impotence or other forms of sexual dysfunction, along with hypertension, and in some cases, baldness.