Apart from it's a HUGE security risk to have your players log on to just ANYONES server, no MMO does this for a reason, I get the feeling you're not exactly well read on the security measures MMOs take to keep players safe from you know being hacked, unlike a game like "Call of Duty" having your MMO account hacked is a HUGE deal, as you'll lose months of progress to someone.
Unofficial servers aren't p2p for the record, they are hosted servers that people join, it's not just running on everyones PC. MMOs CANNOT be P2P, it's just not viable.
Also my MMO with Atavism isn't a crafting or building MMO? You can easily just not have this feature, I don't use it because like you said it's a mess to upkeep.