Maybe why they are advertising it now? I mean like you said both are prominent pro's having gotten contestants to finals when you compare to other pro's who've had their own tours who haven't had the same success.Vito & Dianne are the two pros most due an early exit this year after Fleur/Ellie and Tyler/Bobby the last two series, so interesting timing to go on tour.
The only tour IMO which was on an odd one is a Graziano solo tour as he hasn't made much impact on the show; at least Kai & Nadiya had the selling point of being a pro couple; going from the sales of both of those tours from what people posted on here it showed they weren't doing as well.