A wider audience. IDW has many all-ages books. The same kids who are reading Star Wars Adventures might give a samurai rabbit a try. Usagi has always been an all-ages book, but it's never been at a publisher that courted an all-ages audience until now.
I’m curious: are IDW comics distributed in places that Dark Horse can’t reach?
IDW had distribution channels into places like Toys R Us and other mass market retailers, but I am not sure what is left of those channels after TRU went bankrupt. It wasn't necessarily the same books sold in the direct market, it was stuff packaged for those stores featuring kid-oriented comics.