1.66 was a big patch alright, the last one was 1.69 which was 6 years after release. It's a good reason to support it because it was played a lot though!
I had no idea they felt like that about it, I can understand they must be disappointed other games of theirs didn't have that sort of longevity but I'm surprised they regretted it.
I think the main campaign is quite weak compared to a lot of RPGs really, HotU was okay but the core NWN campaign was 4 levels of going to 4 quarters and killing something. There were a few nice parts but nothing much when even compared to Baldur's Gate for example. Maybe I should replay it though, it has been quite some years since I played through it so perhaps it's better than I remember.
I feel the same though in regard to waiting to play a game with similar possibilities. But I still don't see anything replacing NWN for me.