I think it keeps the story exciting, though mine always seem to happen by accident. *shrugs*

They make a story more exciting.

I had a person comment on a story saying that they found it annoying when authors did this; nbd, we all have our own opinions. I kind of wanted to see how everyone else felt.

For me I enjoy reading and writing them. As you said; they make the story more exciting. But for me it also just works better and feels right? The reviewer said that no cliffhangers make a fic look like more like a novel and that got me thinking. It made me realize that I kind of write fics like a TV show. I feel like it makes more sense to use cliffhangers at the end. With a novel you can write straight through because the book has already been purchased; the reader can just go straight through. With a fic you need something to keep the readers hooked as you write the next chapter. Hence why it's like a TV show.
Another reason its like a TV show is because episodes come out weekly so it makes more sense to end with a cliffhanger. Likewise fics can take up to a week to update. Whereas a novel is already done when it is typed so you don't need that kind of hook nor end point.

The only pit fall I can see is that a cliffhanger might interrupt the flow (in a sense) for someone who is reading a fic that has been complete.

Anyways that review was definitely food for thought and helped me realize why I make certain decisions in my works that I actually didn't realize I was making lol.

^Novels can still have cliffhangers at the end of chapters. And trilogies or serialised books often have volumes ending with cliffhangers.

That's very true. Maybe I should point that out to said reviewer lol. But I feel like that would come off as being salty or bitter.