Should You Allow Comments On Your Blog?
The short answer is Yes! You really should allow for people to post comments on your blog because that makes your blog more interactive and also too people may return to your blog again and again just to see if there has been any response(s) to the comments that they have added.
However there is a problem that comes up and that is that sometimes people will leave a comment on your blog that really isn't a comment but an attempt to either advertise or just plain-out "spam" your blog.
In that case it would be a good idea to allow comments on your blog but but you should also moderate the comments first before you decide whether or not you want to add them to your blog.
Blog sites such as Blogger.com does give you the option of being able to moderate the comments before you post them to your blog