That's one of those questions that invites a dishonest answer. When I started I convinced myself that I was writing to improve my writing skill. When I look at my stuff over the last ten years, though, I think I'm going downhill.
I think every writer, or at least this one, wants to be taken seriously, by which I mean I would like people to engage with my ideas. In some ways, I think my audience is larger than expected. According to Blogger, I get about 1000 pageviews a day (my other tracker says many fewer), but there are only a sawmill operator's handful of people who often comment. A few more weigh in infrequently.
The articles that get the most pageviews (usually on politics) are often not the ones that get the most comments.
Anyway, comments are usually appreciated, although they often bring out my mean streak.