I rather keep more people in the server (more money for ankama) than to make the few (multiboxers) happy. Multiboxers now don't even pay for their alt accounts anyway, specially after they get epic/relic.
That sounds like that would be the perfect solution for ankama to keep their revenues up.
I've always been a huge advocate for multi boxing because I feel like it opens new levels of strategy when you're controlling more than one character. I'm certain this will help make the typical wakfu player stick around like you suggested too.