Those hubs that do will not have them enabled - now nor in the future unless VM change their mind.
Personally, I don't think it's wise to enable the USB port. People will connect disk drives and then wonder why things are buffering, slowing down and so on when the NAS is being pushed. Then VM will have the support headache and that's likely to be the driver behind not enabling the USB port.
A third party router, though, will have more power and memory than the el-cheapo hubs and their USB ports are enabled.
Yes they have, but are not connected for any data use.
Possibly power for charging a phone, but I've never tried it.?
No, they are simply not connected at all.
The way to go, as Seph says, is to buy a decent router and put the hub in modem mode. My Asus router has two USB ports one of which is USB3 ... perfect for connecting a hard drive that all devices on the network can access.