Uh, yeah there was? Go dig through the wayback machine for Jensen Harris’s blogpost series about the design of the ribbon, or watch his MIX08 talk on it; he was the design team lead for the change, and the reason they did it was because the old UI was failing their users. There were usability studies done during the ribbon design which fedback into, and changed, how it worked to adjust to ordinary people’s expectations and needs.
> “I would think that it would be easiest for new users to have options sorted into neat menus”
Like many UI related assertions, absolutely no concrete evidence is being provided to support this point.