The thing with undead pets and zombies is that there's so much IC precedent for them being dangerous, there's so much history built up around them in game that it's strange for most characters to tolerate them. Just because you know it's not harmful mechanically (yet) doesn't mean the IC danger isn't there.
You say being nitpicky about pets and that sort of thing pushes people away, but so does disregarding more than a decade of roleplay and lore just because people want a certain pet, buff, costume etc. If you want to play with undead things, fine - just don't get upset when characters with good reason to react badly do so.
An item that lets a character raise zombies is a little different to a bashing area though. One is characters using necromancy in orgs that have really good reasons to oppose that, the other is unaffiliated NPCs to hunt.
But yeah, reskins are probably the answer. Make the costume raise clay golems instead, or something. Not sure how to explain the need to feed corpses to it then, though.
Like Krysaliss said, tossing out over a decade of precedent, of roleplay and of lore-building just because someone wants to have a specific pet or use a costume is bad.
It's even worse to then respond to criticism with "It's an artifact shut up" and attempting to shut down discussion rather than allow people to actually, y'know, roleplay. That kind of behaviour really puts people off. Instead of anyone saying "Hey, let's see what the city thinks", or "Let's do some research", the response was to threaten IC harassment and even add new city laws to make people suffer for that disagreement.
Is it any wonder people don't try to do anything meaningful when the response can be like that?
As for the undead items: Those artifacts should never have existed in such an unambiguously necromantic form in the first place, at least not available on the wheel or to all circles. Artifacts shouldn't be visibly anti-magick, magickal or demonic/undead in nature*. Almost anything else would have been fine, but undeath and zombies in particular are unambiguously bad for a wide number of IC lore reasons. I mean, IC we've had invasions of those kind of zombies and we've had undead invasions too - The zombies in particular spread virulently, and the costume is way too close to them.
*With the exception of class-specific artifacts like daeggers, of course.
Because the slow bloat of bashing buffs and bonuses only serves to widen the potential gold earned between established players and newbies, and that's a bad thing.
As for aspect perks, I hope that paid monoliths go the way of the dodos and the system returns to being the 1v1/small group conflict driver it was before. Perma monoliths are a horrible idea and ruined a great conflict system.