Mobile Phone advice (OT)

Has that always been the case? If so, I'm surprised I didn't notice. Or the Vodaphone shop just do this for me rather than making a new one up.

Its a more recent thing. Also worth noting that some normal sims are really a bit too thick to be used in a nano sim socket even if cut down to the right size.

In reality they are not needed, but the MNOs hang on to them as its their last vestige of control. Once they phones are allowed to emulate it all in software, the network operator can be pushed further out of the equation. The phone could also in theory use multiple virtual sims at once, and then route calls / data / whatever based on lowest cost provider for that service in the current circumstance. Needless to say the operators are not keen on that as they can see their high data / roaming / MMS / whatever charges being eroded.

... phone malware will have complete control, including access to the MNO root keys, the phone will be under the complete control of the malware and you won't know or be able to do anything about it. Although if there's a NFC payment system on the phone, you'll find out eventually as your bank account will get emptied.

Possibly true, but I can't see a sim saving you from that!