In the grand scheme of things, this probably ranks way up there with watching water boil or something. But, it's annoying all the same.
C'mon, shoe manufacturers. Not all of us live with sidewalks and grass. Not all of us have full-time housekeepers to sweep up all the little rocks several times a day. Not all of us have the time or desire to pick out little rocky pieces before entering a building or room to avoid scratching the floor.
What's the purpose of the deep grooves? Give me a good reason and I'll shut up. Well, probably not, but it sounded good.