Do I trust Apple to make awesome laptops and cell phones? Yes.
Do I trust Apple to keep OS X open to third party development? Yes, I do. Mostly.
Do I trust Apple to keep my personal email, email that might contain passwords and account names, secure and safe? Probably not, which is part of the why I don't use my iCloud email account.
Do I trust Apple to not sunset iCloud email in a few years, invalidating my @icloud.com address that I would have handed out to everyone, leaving me high and dry? No, I don't - and I think that's a much more potent danger for anyone using their @icloud.com email account.