Yeah, I've been shocked by how easy it is to get a brand new router and set it up with the same SSID and password and every device I have auto-connects like it's the same thing. If you have the AP password, it's trivial to set up a fake second router in the same vicinity (you don't even have to touch the original one) with a stronger signal and have everyone connect through your gateway.
Of course, once you have the AP password there's a lot you can do to the network traffic anyway, but it'd still be nice if the computer would pop something up and say, "The configuration of this device does not match the known configuration - do you still want to connect?"