Strange - the fact that Apple is not trying to make money from passwords seems like a good reason NOT to use it. Though I don't have much experience with keychain so I can't comment on that specifically. (I do have a lot of Apple devices I like though).
I feel more comfortable when a company is trying to earn my money by delivering a good product with good service. Of course that doesn't always work out, but I feel it's a better shot.
Well, Apple isn't directly making money from selling subscriptions to the iCloud Keychain, but it's a fairly important factor in making iOS and macOS straightforward to use for many people (including me). So the indirect business case for keeping it around and performing well is pretty sound.
I feel more comfortable when a company is trying to earn my money by delivering a good product with good service. Of course that doesn't always work out, but I feel it's a better shot.