I understand your argument, I really do. however I dont understand any good reason to disable to single player mode from d2 (which the char was not able to play on battlenet, and therefore not able to access the "real money" market activision set up (in convinced this is an activision move, and not something blizzard would have done prior to being bought up) I simply disagree with the way the game was handled. Hell I pre ordered, pre downloaded, and still couldnt play for 2 days after it was "released" all because of server issues. If that the the route all games are going to go.. i guess I am not a gamer any longer. Thats just me, but I will not deal with that, Ill keep playing super mario world and D2 and be happy.
I am not the other guy, but maybe I can clarify: It is an online game. That is a fact. You may not like that, you may not have played previous Diablo games online ever, but Diablo III is sever side. It is an online game. That is not an argument, it is a statement of fact.
You are free to not like that and not buy the game and mention how much you dislike the fact, but it is still fact, not an argument. I agreed with their decision here, but I hope they (like me) look at it in retrospec and say "yeah that didn't really work out as well as we had hoped". I mean I only ever really played D1 and D2 online and I was very happy about very realistic changes to drastically reduce cheating and hacking. I was also excited about the (much less realistic) idea that maybe gold & item spam would be reduced by the RMAH. That said, in the end it wasn't worth it and it didn't improve either enough to justify doing it again. Overall I got enough hours out of D3 that I can't really hate on it too hard, but it just wasn't that good of a game. An ok game if you will, and I agree that I hope they drop online in the future.
Basically, I agree with 99% of what you are saying, but its not just 'add on offline and lan'. The game was server side, that was the way they wanted to go.