I can't play for a while because I have my laptop while house sitting for someone, but I was a ways into BBI by Thursday evening, and the shine is really starting to wear off for me. I think this happened when I played the PS3 version years ago, too.
I'm not sure what it is, exactly. I think it's a combination of things. For starters, there are hundreds and hundreds of items and consumables to pick up, with samey copy-paste icons (there must be thirty monster parts that use the "pile of bones" icon) that make visual identification for sorting and combining a pain; plus, 90% of them will never actually be used. For example, if you were to load up with three of every type of debilitation curative, you and your pawns would be staggering around with massive encumbrance, so realistically you have to combine or sell off the crap and just use cure-alls. On top of it all, you never really know which items you'll need to upgrade equipment, so grabbing everything in sight is strongly encouraged.
The weaknesses of pawn AI become super-apparent once you really get into BBI. I feel like I'm herding retards. For example, some mage will try to cast Anodyne, then hop away because an enemy is near (though not actually directly attacking the mage), then start casting High Anodyne again, then hop away again, et cetera. I have no idea where bow-wielding pawns are actually shooting, but they're not doing any real damage (including rented pawns with 2000+ attack) except to mooks. They just die constantly during boss fights. It's funny how bad pawns are at avoiding damage given the hopping mage thing I described earlier.
On the topic of gear, before you can upgrade past Dragonforged, you first have to get it Dragonforged. Guess I'm supposed to go farm Cursed Dragons, BBI Dragons (if those exist) and the Ur-Dragon, but what I actually want to do is continue exploring BBI, and it takes ages to kill a Cursed Dragon currently when it comes to feast on dead enemy corpses. I can handle the fight from what I've experienced of it so far (a good five minutes), but I don't fancy spending 45 minutes whittling off 8 health bears with shitty gear, and that's hammering away at its heart. Then there's the cursed gear you have to purify, which they're doling out so slowly I suppose it'll be 20 hours before I have an entire armor set put together.
I'm sure I'll figure it out when I get back, but I feel like it's a slog designed to waste my time, and I'm normally very tolerant of "time-wasting" shit in games like these. I've never particularly felt that Dark Souls or Monster Hunter were wasting my time, for example.