Have you noticed it's everywhere now? Even gravy and ranch dressing and preserves become various kinds of "dipping sauce" on menus. Maybe it's just that there are more foods with sauces, or foods that need sauces, or more finger foods?
I don't know why the term annoys me sometimes. I'm afraid I'm getting that crazy old man "Get off my lawn!" disease and I'm gonna wind up on some random child's porch telling them about Country Time Lemonade some day. I suspect it might be that I am resistant to the trendiness of it. I react similarly to the terms "Meme," "Tone-deaf" (when not applied to music), and people getting their drink "on" or their party "on" or their game "on."
Also - and this is even more crazy-sounding - it might be just the sound of the word "dipping."; it's got kind of a chirpy, pretentious "ihh" to it that makes me think of tea and crumpets and pince-nez. I imagine the request for "More dipping sauce!" sniveled through the self-righteous nostrils of an unctuous, irksome ornithologist with yellow gravy in his beard. I always hear it in the "Knights Who Say 'Ni'" voice.
"More dipping sauce! More dipping sauce!"
Stop saying that.