It's not really hidden; it's under Devices, not an illogical grouping with other device-related commands. But if you want to comment to Apple on the subject, you can do so via their feedback page:
I have owned apple products since 1990.
I can't stand apple apologists.
So here goes:
If the Transfer Purchases option was visible and now it's not, that's the definition of hidden.
Perhaps when iTunes warns that I should transfer purchases, it should provide a button or direction on how to do that in the new and improved iTunes.
If the amount of time we've spent using Apple products amounts to a hill of beans in this matter, I've owned Apple computers since 1978. And if the fact that I don't agree with your assessment makes me an "apologist" in your eyes, you're welcome to that opinion. I really don't care. In any case, there's no point in arguing with me on the subject. Again, if you want to comment to Apple, use the feedback page.