Absolutely. We're seeing that with Will and AJ on BBUK - they're bringing something fresh to it that Davina or Emma could no longer offer and don't have the baggage of their predecessors, but also have enough knowledge of the history of the show to be able to reference back as necessary too. The completely pointess (and almost always has been) "Please Do Not Swear" line in the eviction announcements pretty much only continues as a nod to Davina, but AJ has now completely made it her own.
Sonia pretty much only hosted the Seven version because they signed her to the network with nothing to do really and didn't have anyone else obvious to put forward for the job, and weren't willing to look beyond the obvious. In her defence I do think Sonia suited the role she had on Seven much more than the role she had on Nine, but on the Ten relaunch we need someone who can handle live television and interact directly with other human beings.