Just a quick note. Like most people should, I hate Skinner boxes. I suppose some people could think of City of Heroes as a Skinner box, but I never really did.
For one thing, the main reward of the game--leveling up and obtaining rewards--wore pretty thin after a pretty short time to me. Even the Incarnate stuff, I didn't really care about that much. Interesting factoid: I never got any character that last Incarnate unlock (what was it called, hybrid?). In fact, I never did the Magesterium trial on any character. I kinda hope that someone posts video of it so I'll know what it looks like, but I just never felt the need to. There was reward, but the reward never really pushed my triggers like a classic Skinner box does.
For another, the main reason I played the game was just because I liked playing the game. In fact, a lot of my "playing" was done vicariously through Belle, who would play while I sat working on some new site or answering e-mails or whatnot, and I'd help her out if she had any questions or needed assistance with anything particularly hard. But most of the time Belle played, she wasn't actually doing much in terms of actual game stuff. She would spend hours working on easy missions, talking to friends, training new players, etc. Point is, Paragon City was just a cool place to be. I liked flying around buildings, beating the snot out of Nazis, screwing around doing nothing in particular.
Some people argued vehemently when they released the Super Packs that that was essentially a Skinner box. I disagree with that, too. Yeah, I supposed you could waste a crapton of money on them, but realistically, 1) you could also get them for free, and 2) unlike something like gambling where you can never have enough money, if you bought enough Super Packs, eventually you got "done". And unless you were really damn unlucky, getting "done" normally didn't take particularly long or THAT much money. I bought one of the super mega packs of Super Packs once, and truth is, I think I had some of them left at the end just because eventually, I got tired of opening them.
Anyway, I just don't see City of Heroes as in the same league as games that I feel are designed specifically to be more addictive. Sure you could spend a lot of time and money on it--and I did--but that time and money was spread out over eight and a half years. And honestly, most of the money I spent on the game was in outside costs, like hosting web sites and traveling to Mountain View for face-to-face events.