As an example, for a while I was manually entering my weight every couple days. After two weeks or so of doing this, the data simply vanished without a trace. This happened again after one of the early updates. After that, I simply gave up. Yes, a bug report was sent, but who knows what really happens once it goes through the 'Gates of Radar.'
If OSX/iOS were more open source (beyond the kernel and some libs), I think it would be easier to get external developers contributing valuable fixes and offload some support to the community.
It doesn't make much sense to keep the OS totally closed, because the business model is in selling good HW. Sure, control the platform end-to-end ensures quality, but delegating some can be mutually-beneficial.
It's like a small business owner "control-freaking" so they don't put out napkins for fear people will take too many, making it a pain for everyone to accomplish a common task. There is a reasonable amount of control / final say-so that's necessary, but there is "penny-wise, pound-foolish" also.
But maybe if Apple open source Mac OS X, which you do want to use despite the annoyances, then open source will magically help it become perfect?
Two bads always makes a good, right?