Think of it as an intermediate slap on the wrists ... somewhere between just turning all the duped items into monk's robes and invoking the "Internet death sentence" to blacklist all accumulators forever.
Personally I think if there really are people who lost one account out of many and were truly ignorant, they should take what they were hit with as a warning that they had become part of the problem and that if they don't start being more careful about their suppliers, because next time the response could be even harsher.
We all want faster action on exploits, we all want a safe marketplace where you just go "I see it, I buy it", but UO is too complex to be completely bulletproof. UO is at times more of a community more than it is a game and there are rules that go beyond simply what is possible in the client. Trading in questionable items is like swearing, harassing or scripting ... things that are mechanically possible, but still forbidden. You can't trust the game code to prevent you from breaking the community standards. If you're going to be a high end merchant dealing in volumes that would get you targetted, you need accept this as the risk to your reward. I know that's a really scary thought because there's no little warning flag that says "if you touch this, you will go grey", but the real-world equivilant is to be caught in possession of stolen property - if you own a pawn shop, most jurisdictions demand you do due dillegence on your clients.
Now if people have constructive ideas on how to seperate the trustworthy from the untrustworthy, move more of the burden onto the game's code and restore faith in the game's open markets, now's the time to suggest them.