Design in our daily lives should be seamless and unnoticed. Well designed items flow in and out of use, and we hardly think twice about using the things we do.
This changes, however, when you have a physical or mental limitation that restricts your use of objects designed for the masses. If you have a crippled hand, you may not have the dexterity to open a child-proof medicine bottle. The depth and breadth of accommodations this creates is vast. Do all objects need to be designed with accommodations in mind? No. But sometimes, universal design is the best practice.
Public spaces, generally, need to be available and accessible to all individuals, regardless of mental or physical limitations. This can be seen in wheelchair ramps and simple signage at building entryways. More complex design can be seen in ramps at pedestrian crosswalks. While it seems reasonable that wheelchairs benefit from these ramps, the textured panels also signal to blind walkers with canes that there is danger here. Bikers and strollers also benefit from these ramps. Universal design, in this case, promotes diversity.