The philosophy behind this is flawed.
Why would you decentralize a list? A list by nature is an arbitrary way to centralize something into a category so I can't see the appeal, or the logic.
Is it that much of an issue or a hindrance to the operation of #hive?
Sorry, but what you're saying makes little sense to me. Lists, of themselves, are neither centralized nor decentralized (and neither are categories). And categorization is pretty fundamental to knowledge representation and reasoning.
Is it important to protect users from accidentally sending funds to phishing accounts? Yes, it's very important. Even now, people continue to lose money because exchange wallets don't typically give these kinds of warnings. But at least the main frontends do now (well, a couple don't yet, but will soon I think).