Sadly the VM TOS does nothing to stop stupid ppl who brick their handsets from going to VM and complaining and calling in the lawyers and in the end that's what will put a fork in rooting handsets and make sure it's not done again once and for all.. Also abusive tethering which by the looks of the occupy wallstreet crowd (Napster Kids) will happen a lot..
How many people do you know will hire a 300/hr attorney to fight a company because they broke their phone?
When Verizon added this clause they started to repair/replace the device then charge your bill for it. They put a disclaimer in that you had to sign saying you agreed that if they found the device damage not to be covered by warranty then they would charge you via your phone bill. Several people tried to fight it but the attorney's shot it out of the water because of the TOS and disclaimer.
This TOS change actually can stop people from doing as you say. When you agree not to hold VM responsible for what you do to the device and also agree that if you ignore those warning and break it VM has the right to cancel your service. You have very little recourse. You can write letters, call CS, or whatever your heart desires, it wont do any good.
Vm is not going to waste the resources necessary to monitor who is and isnt rooted. Think about that. It would take atleast three people to do this and VM is cheap enough, look at the supposed updates for this phone and the Triumph. Low overhead and high inflow is what they are about.