Ergonomics is a common consideration in most areas of the workplace and safety knives are no exception. However, people mistakenly think that the only ergonomic concern that needs to be addressed with a safety knife is that it is comfortable to hold. I agree that comfort in the hand is a top ergonomic priority, but there are numerous other points that frequently go overlooked: 

Safety knives cut most general industrial materials with ease. Safety knives never make a cutting task more difficult, they just make it safer. Usually if it's difficult to cut with a safety knife it was difficult to cut with a dangerous fixed blade knife too.

Proper cutting techniques can reduce and eliminate lost time from accidents and increase productivity.

Technology is always progressing and moving products forward. The safety knife industry is no different. First, fully automatic retractable knives developed in the late 90's made lacerations much less likely to happen. (More about that in a different article of mine.) 

Many workplace injuries are caused by a lack of focus while on the job. Whether you are operating heavy machinery, driving a vehicle, or using cutting tools, you are far more likely to make a mistake when the task you are doing does not have your full attention. Workers who utilize potentially hazardous tools and equipment are more likely to be injured when they are not 100% focused. There are many reasons why workers may not be fully focused, but one of the main reasons is lack of sleep. Studies have shown that sleep deprivation inhibits cognitive functions, such as alertness and attention. It can cause slow responsiveness and a wake state of instability. Attention lapses, “brief moments of inattentiveness”, are the main reasons for a decrease in cognitive function due to sleep deprivation. Imagine trying to operate potentially dangerous tools or equipment, such as a knife, with brief moments of inattentiveness. A worker may accidentally slice a finger or drop the knife onto their foot. The possibilities are endless.