From: https://movieweb.com/oscars-voice-acting-category-needed-why/

It appears that the perception of voice acting as a laid-back job has infiltrated the general public mind. This emphasizes the significance of having an annual Oscar category where a diverse range of voice acting talent may be rewarded for their hard work and dedication. Working as a voice actress is far from "the easiest job in the world," as Chris Rock phrased it at the 2012 Oscars, and having this profession recognized through a Best Voice-Over Performance category could help to change that view.

Although voice performances are eligible for nomination in the acting categories, no one has ever been recognized for them, likely because Oscar voters prefer live-action performances. Aside from Hamill and Johansson, this new category would be a way to recognize less well-known faces who have nonetheless played important roles in the portrayal of many cultural icons, such as Jim Cummings, who has been voicing Winnie the Pooh since 1988, and puppeteer legend Frank Oz, who is responsible for most of your favorite Muppets and, of course, Yoda.