They allow changing Wifi settings without even unlocking the phone.

Be really careful about letting anyone touch your phone, esp. at conferences/airports. A hacker could setup an easy MITM Wifi, to capture all of your traffic. But, now, without unlocking your phone (but still getting their physical hands on it), they can connect your phone to the Wifi SSID of their MITM attack network.

Then, you're just surfing facebook, email, bank sites, & everything looks 100% legit. Meanwhile all of that traffic is going through their wifi & they can capture your sessions & impersonate you. Nasty stuff.

All it'd take is one malicious network, and a band of attractive agents to shmooze unsuspecting people into showing them their phones to harvest tons of sessions & data.