Torchlight 2 is a little double-edged. Moddability is nice, but I think it provides a disincentive for the publisher to make expansions. If you can mod a character class or a campaign, then you can host it on a download site (possibly not even on purpose, because maybe your mod consists of tweaks and balance changes but happens to contain the entire expansion 98% unchanged). Since it isn't good to police mods, the publisher can't really sell more things to extend or improve the game.
An expansion pack would at very minimum include new art assets, assets which in turn could be used by modders whose mods would then require
the expansion pack.
I guess the argument could be made that mods hurt the market for cheap uninspired DLC, like costumes and stuff where modders can create non-identical content that's of similar quality. However, a proper expansion with real content complements rather than competes with mods. Look at the Baldurs Gate Enhanced Editions as an example. There's an example of a game that's been modded every which way, and the a re-release was still
It should also be noted that T2 has a lot of D2 developers who weren't involved with D3. D3 was mostly a matter of an oversized company iterating on a brand after the creators had jumped ship to do something else.
I got a whiff of executive meddling there. I'm also a bit uneasy about Blizzard's senior creative staff; I get a real "George Lucas" vibe from them in that they have reached a point in their careers where they have no editorial oversight and half of what they spew out is crap that no one is allowed to challenge. I remember playing Wings of Liberty and really liking half the campaign, but finding the other half absolutely cringeworthy
People matter. Companies and brand names don't.
And often times it's people you've never heard of. The little guy in a cubicle may not have as much influence on the overall game as the guy in the corner office, but collectively there are a lot
of little guys on any game production.