In a lot of GA applications the effects of mutation are negligible. Given a large and diverse population, crossover provides enough variation already. Mutation

In a lot of GA applications the effects of mutation are negligible. Given a large and diverse population, crossover provides enough variation already. Mutation will only be necessary to escape if the entire population has converged to a poor local optimum, but that doesn't tend to happen often in practice, and even if it does, there's no guarantee that mutation will help; hence the lack of focus on mutation operators in general.