Agents are the new search engine - a majority of people are starting to get recommendations and answers from them. So asking this is like asking "what is the benefit of making any resource more available to search engines?"

The answer is discoverability. which is pretty critical for any business

I've heard CTOs saying they don't consider buying any product that is not AI agent friendly. Which means they must come with AI skills, MCP Servers and so on that agents can use it to do stuff. You may not like it, but that's almost certainly going to be the future.

agents are becoming the de facto standard interface for everything, whether you like it or not, so it depends on the intent you have for a project, or "product" as OP phrased it, which has a more contextual implication that the intent is to get others to buy it

Behind an agent is a human that might use the product. I think customers/consumers will demand that their personal/subscription agent can access the product.