It can be a differentiator but it's a hard one to sell. Telling someone your software is easier to use will usually be met with an eye roll or a snarky "of course you think it's easier to use, it's your software...". Ease-of-use needs to be either demo'd or experienced during a trial period. The question is how do you get a potential user to that point?

Further, you'll notice very few companies that make highly usable products advertise them that way. Look at an Apple ad or Netflix or Toyota. Very rarely do they ever talk about ease-of-use. They always focus on what the product can do and how it makes you feel.