Hi ladystocking and let me add my welcome. I am especially pleased to read your reason for being here because my wife, though I love her dearly, is exactly the opposite of you in this. She has no desire at all to try to understand or appreciate my tickle fetish and would be happier if it just went away.
As to why your husband likes tickling you, really only he can tell you that, if he can at all. Truthfully, I can't say why I like tickling so much. I just know that it excites me a lot when I see it or am directly involved in it. I guess for me, since I also have foot and nylon fetishes, it is also another way for me to enjoy those. I also really enjoy touching and cuddling with a woman and tickling can involve that.
Hope this helps you a little.