I agree this is pure spamming, but I don't think they're going to disable it. "Somewhere in the distant 2.0 version, perhaps..." is the answer (note that I'm writing this nearly a year later).
By the way, it's not really about a "much needed" feature, it's about a "much hated feature" - all they need to do is to remove it. Someone programmed it in on purpose, I guess there must be some profit in that.
I wish someone had some workaround for this. All I can think of now is running "cron" on Linux, say, every hour with "insync reject_all_new_shares" - it would at least partially free me from doing it manually each time.