You are right, newcomers will understand the error message.
Personally, when I joined Steem, I voted a lot, even though my vote was worthless. I would have been frustrated to be held back. The weight adjustment and error message are, I admit, minor obstacles to voting, but they require extra clicks. Some people will wait instead of adjusting the weight, and they may consult other websites in the meantime. I think there will be far fewer votes.
Every change makes people happy, indifferent, or frustrated. I'm tired of breaking changes.
Hive is losing its appeal, markets are losing volume and liquidity, and arbitrage and market maker bots are leaving. This is not the time to lose more users, even if no one will leave because of this.