The characters were underwritten?
Sure. One LotR movie has more characterisation than the whole of this trilogy. Bilbo is barely in them, instead there are 45 minutes of some guy carrying gold and then 45 more of a bunch of CGI characters running amok, etc etc. Maybe it’s just my crazy brain but I kind of expected with there being this much running time that they might expand things that matter since the ensemble is quite large. But instead a dumb love triangle briefly and the rest don’t even get dialogue. Go watch some of the production diaries and laugh at how the cast describe who they’re playing.