Absolutely offer people an optional blank text box. This drives me up the wall, and I use one of the standard titles (Ms.). Personally, I wish we'd just make 'Mx.' happen, to give people a gender neutral option. And it drives me up the wall when they include "Miss" (what you'd use to address a young girl), but not "Master" (what you'd use to address a young boy). If we're going to be antiquated, let's do it right, people.