The question that will answer your question is:
What do you expect people to comment about?
I mean, what is there to say to a movie review? That you write well? That you accurately summed up the plot? That you missed the beaver shot at 0:34?
Most people read movie reviews to decide if they want to see a movie. They read the review, then they see the movie. They don't comment on the review, because they are not actually interested in the review in itself. And once they have seen the movie (and could discuss the movie with you), they don't read a review but talk to their friends, post on Facebook, or on a more popular review site like Rotten Tomatoes, rather than commenting on a lonely site where their comment won't be read.
I can't come up with anything that I would want to write in a comment on a movie blog. So what kind of reply do you expect? If you don't know, then how are your visitors supposed to have that insight? And if you know, write in a way that makes people want to give that kind of response. Write controversial, if you want a heated debate about morale. Write about topics that interest your target audience (love, sex, food, clothes, crime, loneliness ...) and use the movie review as a frame to fill with those topics.
But in the end, even if you have the greatest content, it all comes down to attracting a critical number of visitors. If there are too few visitors, they will see that no one comments, and they will leave feeling disinclined to comment themselves. It is like an empty dance floor. No one wants to be the first. So, in my opinion, you will have to pay to attract lots of traffic for some time, until the number of visitors and the number of chance comments and backlinks gain a critical mass to drive your blog by itself.
With a generic site like a movie review blog (of which there are thousands, if not millions), you will need paid advertising to overcome market inertia. If you want to attract a following without paid ads, you have to create something unique (and not do movie reviews).
Edit:
I just read part of your review on the last Hobbit film. You got a comment there, and it says, very harshly, something very similar to what I find: that your review didn't engage me. I have a hard time pinning down why this is so, but somehow, when I read it, I don't really care about what you have to say. You go on and on about what you dislike about the movie, then add what you like, but that does not really matter to me, because I am not you and I like or dislike movies for different reasons.
So why do I like some movie reviews that I read? Either because they give me background info that I don't have on the persons or politics behind the movie (e.g. see the "Development" section of the Wikipedia article on the Hobbit trilogy – how is that background reflected in the film?), or because they contrast the movie with general screen writing or movie making methods/theories/technologies/etc. (e.g. does the Hobbit movie have a hero, or a three act structure, or how do advances in computer animation technology set it off against older Hobbit films?), or because they use the movie to look at culture, society and politics in general (e.g. how does Jackson's Hobbiton differ from Tolkien's, and what does that say about our times?).
Your review is just a description of the movie and a judgment of wether it was good or bad. If I wanted to decide about viewing or not viewing the movie, a Wikipedia plot synopsis is better for that, because it is concise and to the point. If I wanted to read something intellectually stimulating (independent of having or not having seen the movie), that is completely missing from your review (at least the one that I read).
I feel that you need to read some good movie reviews, maybe in some national newspapers, and analyse them, to understand what they actually do. They don't summarise the plot, and they don't (for the most part) judge the film, but they use the film to do something else. And that is engaging and makes me go "But...!" and want to comment.
After that general critique, lets look more closely at your first sentence as an example of your writing. It reads:
A lot of people love the Lord of the Rings trilogy, and it isn't hard to see why - you've got an epic, sweeping story of an adventure over an imaginative, richly detailed work with it's own unique back story that boils down to a story between good and evil.
In your first sentence, you presume too much (e.g. I didn't love the LotR trilogy, although I'm a fan of the books), you raise a false claim (in truth it is quite hard to explain why so many viewers, who did not previously care about fantasy at all, did go see that movie and now buy the books), and you spell out a banal and common phrase (about epic and good and bad) in too many words, making it sound like you repeat something that you have read elsewhere.
I started skipping your text at the first sentence! I may not be your target audience – you need to define who that is and not just write for yourself! –, but maybe this will give you an idea about how your writing is perceived.
Also, do something about spelling and grammar. "they are maybe to long" (too), "3 hours had past" (passed), etc. Maybe get someone to copyedit your writing, it is often too difficult to find your own mistakes.
Generally (as a judment on my part) your writing is okay and a good starting point, but you got a lot to learn.
And please don't let my opinion discourage you. Here is where the wheat is separated from the chaff. Those that will make it as professional movie reviewers ignore the opinion or grow a thicker hide, digest the critique they agree with, and keep working to get better. What you do isn't bad at all, it just isn't brilliant enough to succeed in a highly competitive field such as movie reviews.
Good luck!
