A number of my ships do not use docking computers - these include ships intended for use on planet surfaces (doesn't work there anyways), dedicated combat ships (need room for armor and other combat necessities), scavenger ships, and a few other types - again largely because the docking computer is either useless or takes up space much better served by other modules.
However, there are few ships I do use a DC on - freighters, smuggling ships, system-hoppers, and the like. On these ships, the small slots occupied by these would likely have little else of use to fit in them, so why not? With at least one of my freighters, the DC saves me a good bit of time, as it can carry out the docking process while I'm plotting a course and be ready to jump out of the system as soon as I've offloaded/loaded cargo.
And if I need to, I can always take manual control and fly myself.