I take offense to people wearing a SOD if they have no connection to the Jewish religion or culture because it cheapens the meaning of the star. It has deep religious and cultural association that the Jewish community holds dear, and when people wear it because it's "fashionable" they're basically rendering the meaning of the star null and void.
How is it "helping" the Jewish community? It's making a mockery of the symbol. Are the people wearing it because it's "fashionable" taking into consideration what the star means? And are they making any attempt whatsoever to learn about the culture, history, and religiosity of the religious symbol they're wearing around their necks?
Kabbalah and all that nonsense is completely cheapening and mocking the Jewish faith, and I do find it offensive and I think it only makes the people buying into the fluff look silly. The rest of the Jewish community, the ones that have an understanding of what the Kabbalah really is, are all laughing at them. It's ridiculous.
As far as a cross being "fashionable," I know nothing about that, and so I won't argue for or against the propriety of wearing a cross when you have no Christian affiliation whatsoever. But wearing a SOD when you're not Jewish, don't participate in Jewish cultural practices, and don't understand the significance and value of the symbol is indeed offensive to the Jewish community and I know for a fact I'm not the only one that feels this way.
Like LVShoeFan said -- religion is not supposed to be fashionable.