The swastika only took on any sort of evil conotation under the use of Hitler.
There are two variants of the swastika, usually refered to as "male" and "female" variants, the female variant has its arms pointing to the left and traditionaly signifies balance, harmony and tranquility. The male variant has its arms off to the right and traditionaly symbolizes progress, prosperity and forward thinking.
The Nazi swastika was a modified version of the "male" variant. Modified in that it is oriented to balance on a corner rater than have one of its sides paralel to the ground as is traditional.
In antiquity, many cultures around the world used it at various points in history and it was never evidenced to have been evil until Hitler got his hands on it.
Yes, its illegal in Germany and many other European lands, but put yourself in the position of living there at the time, this kind of symbology hits pretty close the bone for a lot of people even if it isn't illegal in their country.
I seem to remember a news story from the late 1980s that some software manufacturer got into a bit of trouble with German authorities because they created a series of clip art images that included a swastika and an image of hitler himself, both outlawed in Germany. It wasn't a big matter, but they had to eat a bit of crow and recall their package and re release it in a modified form for several European markets.
The swastika has a fascinating history, unfortunately a lunatic got his hand on it and damned it forever, it had no evil on it before him, but now it will only ever be remembered for evil things.