Because they believe (correctly, I think) that AI is going to be foundational to most of the computing experiences we have, moreso over time.

I don't think it's particularly absurd to make an analogy to other foundational technologies. When relational databases were invented, and enabled a ton of new & better capabilities across a host of user-facing software, it would have been strange to let users "opt-out" into the more limited, simpler experiences that could still be supported on earlier data architectures. And what would it even mean, practically? Maintain two separate data management systems, one relational and one legacy?

AI is almost certainly going to be like that, threaded throughout the designs of essentially everything above a certain level of computational complexity.