[toast0]

Availability when utility power isn't (at least theoretically), much lower latency (although everyone else has terrible latency, so kind of meh), desire to spend $60/month for $15 worth of service that the service provider doesn't really want to do anymore anyway. :P

[bombcar]

Be aware that in some areas unless you specify a "burglar alarm" or "elevator emergency phone line" or similar, you may end up with a little powered box connected to fibre or similar.

Some have battery backup and so kind of work the same as before ... for awhile.