This may take awhile to get used to.
Honestly, I am very happy with the way my high school students can collaborate via the LMS we use with our school. I do not see myself additionally requesting that they begin a blog separate from or LMS. The LMS also allows me to very closely monitor their activity.
I do see the value of a blog for a student to keep record of his/her personal and academic experiences, especially college or graduate level. A personal blog also belongs to the author and can be shared at his/her discretion and never goes away. Discussions and activities through a LMS essentially belong to the school which provides the account and when the semester or school year is complete or the student graduates the activities may be deleted to save space.
I liked the suggestion by Sandra Porter in our Pre-Reading #3, that college and graduate students  keep a blog showing their lab, research, and internship experience in order to be able to share for job hunting reasons. Prospective employers can be very impressed with the organization of experiences.
Porter also suggests in "The Ten Commandments of Student Science Blogging" that what you write is what you know and have experienced personally. When asked about items you post, you had better be able to recollect and discuss in detail. Your blog can give prospective employers a platform to generate interview questions. You in response have the luxury of fielding questions which otherwise may never have arisen in your interview and possibly your skills overlooked.
I agree for older students, blogs may indeed have their place.
Candace