It's not exactly customer acceptance they're after. Cars are a market where there will always be some kind of competitor. Toyota knows it's one of the few great automakers in the world; they're not sweating that someone might out-Toyota them. But there needs to be advances in technology and manufacturing to lower the cost of EVs, so more people will buy them. Toyota could try to take the brunt of that gamble (assuming they even succeed), or it can open up its tech and let rivals try to build better tech, which they can then reverse-clone, like IBM making a clone of an IBM PC clone. Once the tech is more widespread and cheaper (and other people have paid for this to happen), they can swoop in and reap the benefits of an even larger share of people to whom they can sell cars.