So, when you read the comments I make on writing, remember that's where I'm coming from. Me, I'd rather die. An old screenwriting tip is to look at dialogue on the page and ask if, merely from the dialogue you can distinguish the characters. Truth is there's one writer writing, one filter, and it's very easy to slip into writing most dialogue with the same rhythm, the same basic vocabulary, the same attitude. Carried away with our own inner images of the story and the characters, we often unconsciously embellish what is on the page with our inner knowledge and falsely see a differentiation that's not there.
Dialogue can deepen character.
I've said before that when I'm selecting as an editor or judging for a competition, the feel and music of a piece have a strong effect on my opinion. Rhythm and smoothness on their own are not enough for a hit, but lack of that essential smooth readability can cause a rejection. It's important that the reader is drawn in and lulled into the dream which is fiction, not jerked out of it, shattering the illusions we have strived so hard to create. The first is monotony, a pattern of similarity in each delivered speech, where line after line of dialogue is the same shape and length almost like a iambic pentameter in poetry. What we have is something mechanical with no joy or lift or variety.