People usually does not always rely on desktop or laptop to use internet. Many of them now access internet through mobile phones and smart phones for socializing, shopping, checking out weather etc. I also use to check various blogs especially those which are optimized for cell phones like FamousBloggers, HellBoundBloggers etc through my iPod touch for any updates and sometimes I also do commenting through mobile devices.
This Infographic shows some strong reason to consider making your blog optimized for mobile devices.
Have you customized your blog for mobile devices?
If not then you are missing a lot! Check out this tutorial by Kristi Hines, it will help you to make your WordPress Blog Smartphone Ready!