The point is that you can get the swine flu more than once.
Yes, that is correct; but because you have had it, the severity of the second outbreak is dramatically less, the duration is shorter and the recovery faster.
Here's the catch. We all have some limited immunity to the Asian flu and previous versions of influenza. Each mutation has something in common with the flu we have either had, or had the vaccine shot for at some point in our lives. So, we can weather those strains pretty well.
No one who has not either had Swine Flu or the vaccine this year has any immunity at all. This is a new strain of bug - no human is immune. We are very lucky that THIS version is fairly benign - however what about next year, or the years after that. Eventually this will mutate into one NASTY bug. If you have no immunity at all; you will get very sick, or possibly die.
Consider, most of the survivors of the 1918 Spanish Influenza outbreak were people who had caught influenze in 1917.