Unless you use VoIP, IM, and/or want email notifications. Not receiving calls through a cellular network is not the same thing as not having communications channels that should be kept up. And while such a standby mode (or softpoweroff...) might band-aid the problem for some users, the real issue is with the routers, and it'll continue to plague people who do want their device always live.

For those who can afford a data SIM, the solution is coming in the RX-51 -- ditch the router, and just use HSPA. (What that does to idle-but-connected battery life remains to be seen, of course...) I'm already doing this with my N810 -- I leave it tethered to my phone instead of hopping on the WiFi at home (even though my router's fine), but I charge my phone (and tablets) every night.