Well, necessary is my word. Just doesn't seem like it's worth the trouble.
Had I been there for a few years, I could potentially have a good case if I wanted to pursue it, and if I felt the harassment had truly forced me out of my job, meaning that after escalating the situation through the correct channels, and little or nothing being done, and six months goes by and the harassment is still being ignored by HR, and all I could do for my own sanity was leave, then, yes, I would probably sue.