This is going to be a bit of a strawman, I'll be up-front about this. I hope that it's not too disingenuous to make a short post knowing this up-front, but... well, there you are.
Anyway, one recent announcement regarding Blizzard's oncoming Diablo III has stuck in the craw of a number of PC gaming aficionados. Looking at this from a gamer's perspective, I can see the impetus for some of the ire - as a fan of both making and using mods for PC games, it's a little bothersome to see a large company who, in the past, has not done little to support modding of their games withdraw that kind of support from a new game. On the other hand, as someone not invested in the series, I don't know that I have the same visceral reaction that long-term fans of the IP do in regards to this. Maybe this gives me some objectivity, maybe it simply means that I'm not informed enough.
Regardless, there's the other viewpoint - looking at it from the view of the developer. I can see through the announcement and realize that the real reason here is that they want to push for a persistently-internet-connected account for one real reason: to verify the legitimacy of the game. There's nothing wrong with this, of course, but it's a shame that even the single-player portion of the game doesn't have the modding accessibility.
This may be a bit of a divergence from the story at hand, but I'd like to wonder what kinds of tangible benefits (or maybe intangible benefits) developers and publishers see from an established modding community. Clearly, goodwill is an easily-cited one, but goodwill as an asset is difficult to quantify, both in terms of how widespread it is and how much value is seen from its presence. Another one is trying to make a little more money off of the long tail; trying to ensure that the game has a little more "longevity" and consequently more shelf life. This is probably also a little bit overestimated. I might say that one of the greatest benefits - and this could simply be me overestimating another factor - could be that modification support simply acts as a training ground for future contributors to their company. By ensuring that these people spend a long time with their game, it ensures brand loyalty, and by ensuring that those same people know their tools really well, it ensures a compatibility with that company and a desire to work there later on.