App specific password problems with iMessage

I'm having a problem. I just want to be able to use 2 factor authentication. Not passwords. I do not want to create a password that can be used that will bypass the pin that gets sent to the device. With the app specific password. It seems that anyone could use that password to get into my iMessages.

My iPhone works with the 2 factor authentication. When enabling iMessages. My iPad and iMac Keep asking for an app specific password. I know they had the ability to have the program send a pin win logging into iMessage On the iPad.

MY main issue is that these are not as secure. If anyone knows the app specific password they could use it to bypass the pin that gets sent to my phone or iPad.