Personally, I don't care what gender a LW is. Usually, it doesn't impact my thoughts on what they should do. However, I hate always writing "he/she", "s/he", or "he or she" or trying to avoid a pronoun completely. I really don't like using "they" as a singular pronoun. "It" would be even worse, so I simply pick a gender. Being female, I'm more likely to assume they are female when the letter isn't clear about gender.