Maybe some people can pretend they're interacting with a real person. But for me, knowing that I'm interacting with a bot would break the experience for me.
This is a similar take I have on one player video games, I just reaaally have a lot more fun in multi-player or MMOs. But a ton of people love the solo run throughs and what not, power to them.
I think it comes down to having a novel experience and one where there are some unexpected twists and turns.