I have been writing to a few fellows (on these dating websites for older adults) who live too far from me to get together easily. Some of the notes are interesting and fun. I'm not particularly looking for a pen pal, but I find that developing a friendship through writing is not necessarily a waste of time.
I have one friend who says by writing to the opposite sex, especially someone who may be a possibility keeps her "in the game" and makes her not feel as lonely.
I do think that if someone writes and they are bright, funny, and interesting, writing to them can be a short respite during the day and something different to occupy our time - especially if we are looking.
Like any other interaction with an unknown person, we have to be careful, not give out too much personal information, and certainly always be aware of the possibility of a scam. That is unfortunate, but it is the reality of interacting on the web.