Torchlight 2 is better than 3, but it's still pretty long. If you're going for plat on Torchlight 2, the main campaign is fairly fun, but the trophy for getting to level 100 was such a long, boring grind that I was pretty much hating that game by the time I finally got plat. I'd recommend Titan Quest instead. It's also long, but a MUCH richer experience in terms of character progession and leveling than Torchlight was.
2 years later.... I just ran into the exact same issue. Did anyone figure out a way to resolve this? Have nearly every other trophy, and now all of a sudden it's looking like it's an unobtainable platinum. Wish I saw this thread earlier...