I suspect they needed an uber-positive pro, one whose entire personality is sunshine and roses, as well as a total fan favourite to hide from the Giovanni stuff, so it makes total sense.
I also suspect that Aljaz struggled to get work outside of strictly - his accent is very strong, which rules out a lot of presenting work, and he didn't have a particularly high profile either.
I personally LOVE him. I think he's exactly what the show needs, so its a great move.