Straps have been shown to increase the odds of serious injuries to the hands, wrists and arms when used with poles. I have provided first aid to more than one person who had a pole get wedged into a hole or between rocks and suffer injury when their hand was trapped by the straps. When used properly, straps do not make the trekking pole any more or less efficient to use. In fact, it is far more efficient to not have them when trying to get to water bottles, snacks, camera, etc from a pack while walking. It is also allow me to quickly transition from using my Leki poles, to not using them when I get to short sections where I don't want to use them. Heck, anytime you need your hands free, like for a quick 'nature break'.
A few years ago when Leki had me test a new model of pole, they had indicated that they were working on a quick release mechanism for the straps because of the injury issue. As far as I know, they still have not been able to solve the issue of the needed force to trigger a release because of the way people have been told to use the straps with the poles; it could cause undesired releases.