Typhonicus is absolutely right in calling BS on the premise that we can't have off-line only mode because cheats/hacks/etc. The only real reason for no off-line only mode is the RMAH money grab. See my quote below (quoted from --> http://us.battle.net/d3/en/forum/topic/8728323766?page=3#60):
We have botters, cheaters, exploiters, hackers, dupers, and gold spammers in D3 and Blizz even screws up their own product through patching. There are pirated hacked together D3 servers. They may be complete, but they exist.
Put up a $10k cash reward for a fully hacked together D3 server that is an 85% functional replica of patch 1.0.8 and multiple hacked together replica servers would be available within 6 months to 1 calendar year.
Blizzard has already failed at keeping the game secure and closing loop holes. Maybe you need more reminders like:
- god mode archon (takes no damage) bug
- monk ability producing extra loot on monster death bug
- crafting dupes that lasted beyond more than 1 patch cycle
- current item dupes that still persist
- 24/7 botting that is going on right now
- multibox botting 24/7 right now in MP10
Yeah I'm going to just say your point was invalid.
As MissCheetah summarized most self found types want multiplayer, achievements, etc. Off-line mode types would prefer LAN for multiplayer in a private setting (not console gaming). I belong to both parties self-found online and off-line mode. Blizzard will not provide off-line mode with or without LAN.