Here’s hoping I can save you folks from coming to blows in this war over words. Or rather, over dialogue.
Realistic dialogue uses a combination of sentence fragments and full sentences—as does real speech. Relying on one technique too heavily makes dialogue sound manufactured. Go too heavy on the sentence fragments and the dialogue will sound choppy, distracting your readers’ attention away from your content to your craft, something you never want to do. Go too heavy on full sentences and your characters will sound long-winded or (gads!) stiff. In either case, if you’re using a technique often enough to spark argument, odds are you’re overusing it. Might your group be reacting so strongly because those complete sentences of yours sound too formal? Be sure to fill them with shifty syntax, to use casual grammar and self-interruptions, and, sometimes, to let them be run-ons. Above all, let your hair down! Full sentences needn’t be death sentences your cohorts fear.