The biggest problem was the degeneracy once it was "solved", instead of organizing around social circles. It led to people feeling like cogs in the machine and skewed play patterns and motivations.

I haven't really given it any serious thought but I'd likely start with trying to more strongly codify the good parts (incentivizing smaller circles inside of the larger structure, making systems for patrons/vassals to play together in more meaningful ways, etc) while highlighting the positive actions that players could do / benefit from. I don't want to say AC was TOO opaque but a lot of it definitely suffered from being over designed for a very hardcore market.

It eventually ended up being a straight line where you could add yourself lower and higher in the line with two different characters, and turbo feed the xp upwards (there were loyalty stats to push up and receive more xp). It peaked with a prevalence of bots that would be parked at the bottom feeding the line 24/7.

Loved AC. Bots kind of killed it IMO (something I feel bad about contributing to), but also new MMOs (WoW decimated the competition when it came out). I remember a portal / recall trick with two vendors, where one would sell a specific thing cheaper than the other would buy it. This was before eBay cracked down on virtual goods. Interesting times.