Is there a level requirement or stat requirement for getting legendary items? Or do they simply drop that infrequently that they're hard to find? Are legendary weapons more likely to drop for high level characters? I'm nearly 150 hours into this game, and have yet to get one.
As with all items in Torchlight 2, Legendary drops are random, though obviously much rarer. I experienced my first drop around lLevel 65 on NG+ with my first character build. However, I've read many stories similar to yours wherein players with your hours do not receive any legendary drops, so it's not uncommon.
Consulting the items on the Torchlight 2 Armory, the lowest level legendary items are Level 54, so it's possible to get legendary drops any time after this level. There are no specific stat requirements to experience legendary drops. Hope this helps. Happy farming.
Yes, legendary items only drop from lvl 50 monsters or higher. Therefore, you are more than likely to find a legendary item in NG + or Mapworks. They are rare and just because you are lvl 100 does not mean you have a higher chance at getting a legendary than a lvl 50. They are just as rare regardless of what lvl you are (50 and up that is).