Radio comms are indeed useful, cables generally have limited length, and honestly they can be a weak spot in the armour (looksee at Neon Genesis Evangelion for a far-out example).
But and However, OTOH, radio comms has its own glaring faults. One, bandwidth. Bandwidth on a wireless system is very strictly shared between all users. Two, security. It's not impossible to snoop on copper or fiber, but radio is just so-o-o-o much easier, making industrial-quality encryption mandatory. So while one user in an ideal world might get 100Mb/s out of a wireless connection, by the time we add more users (OK, on a WAN) and then the encryption overhead, we're doing well if we can get 30-50Mb/s. Ever tried streaming that movie and browsing at the same time? (Which is why both PS3 Media Server and Universal Media Server recommend you don't do it: use CatX for the streaming instead.
And now, with fiber to the whatever, we can still have our faxes (and you won't believe how secure they are), monitored alarms, and PSTN/VOIP telephony!
Would I rely solely on the land-line? Was Humphrey Bogart a sheila? The mobile phone is one of science's gifts to humanity--but in its place as a redundant technology.