This "feature", aside from being a security concern (sending each individual person in a group the contact info for every other person in the group), this also creates a MAJOR annoyance for recipients of these messages even on NON-iOS devices, including potentially increased service fees.
If an iOS user sends a group message, and isn't careful (I'm not sure yet what causes this), it will get sent as a picture message, NOT just a text message. This can occur even when the message contains only text.
Then, if any of the recipients also has iOS, and they reply to the message, it will send a PICTURE MESSAGE reply to EVERYONE the original message was sent to. This means an unnecessarily large number of picture messages are being sent, unintentionally, to a large number of people. Picture messages are still treated differently than text messages (especially for overage fee calculations) on many mobile phone services providers' plans.
Even if it were just text messages, this is still a bad default behavior since many users do not have unlimited texting plans. If your contacts don't have iOS devices, or they don't send group messages, then this issue won't affect you. I think the interaction of these two items is all that is preventing this from being a "Major" issue in the eyes of Apple.
It really needs to be changed/fixed. I shouldn't be punished for having friends with iOS devices and for not having a smartphone with unlimited texting, but currently this is somewhat the case. Receiving picture messages on my phone is fine when they are infrequent, however when I get ten of them at once, and ZERO of them were meant for me, it is extremely annoying, and in my opinion, it is a MAJOR issue.
Message was edited by: Jon Hoffman