Personal preference. I prefer not to have them. I generally am not on tight trails where I would need scrape a rock / tree down the length of my sliders. I believe a lot of people like the idea that the kick out will give the rear of the truck a little more clearance if needed. I just do not.
Although, now that I have a Four Wheel Camper, it would be nice to have that extra spot to stand on to access the roof of the camper. The Trail Gear sliders stick out even with the fender flares on my 2002 extra cab tacoma. That seems to be plenty for me.