It’s the wrong question but it is one that inevitably emerges when you start looking at the effort you put into it and the number of people who visit (and the fewer who comment). See the problem is that the short-term return on investment (ROI) of most blogs is probably small and even fewer blog writers are able to monetize their content directly. There are probably lots of other ways to generate the same level of ROI without blogging. So why do we do it, and should you?
My business does not need a blog. I need a blog. Not in a narcissistic, ego-defining way, but rather as a creative outlet. I do, however, want my blog to be a reflection of my personal and business brand.
So the critical things to ask yourself when it comes to your business and its blog behaviour are: (1) do I have the desire to devote my time in this way? and (2) is my blog an authentic representation of what my business and I stands for. 
The first is all about motivation and interest (it’s what keeps you going, each day or week or month, whatever your planned schedule) and it is a critical success factor. As social as the Internet is now, a blog is still just a person taking a risk by sharing their views.
The second is, however, equally important. To be authentic the blog must reflect who you are and what you believe and stand for. It is what allows you to be interesting and controversial — it also allows you to be wrong sometimes.
So when I have a creative inspiration and a tweet won’t do, I blog. Or, when I am not busy with paid work (or need a distraction from it), I blog. It is as easy as that.