The UK and (originally) German Viva never matched, though. While the other Viva's have had the triangles in some shape or form since 1993, Viva UK launched in 2009 with its current logo. So I guess it's safe to say it's deliberate.
Maybe it's worth noting that the other Viva's are music channels in the more traditional sense. Whereas Viva UK has been, well, whatever Viacom want it to be at any given time!
Maybe they just chose to rebrand TMF to Viva as they had rights to the name anyway and it didn't have the word 'music' in the name. (IIRC TMF stood for The Music Factory, which doesn't make an awful lot of sense anyway.)
The direction has definitely changed for TMF/Viva over the past few years.
It served itself well as a shop window for MTV's programmes on Freeview (aside from the obvious music programming), giving Freeview viewers a taste of what MTV showed. Out of what they showed, Pimp My Ride was one that drew my interest. They also briefly had the kids block, Noggin, showcasing Nick Jr's programmes on Freeview.
October 2009. Completely overhaul TMF into a bigger and better offering - in the process bringing the Viva brand over in the UK - offering a bigger selection of MTV and Comedy Central programmes to the Freeview crowd (the likes of South Park come to mind).
With Spike's launch, Viva devolved into a traditional music channel - with none of the coverage or hours it commanded on its main platform. The original plan was to pull it off Freeview, but salvaged it in the end with reduced hours.
In retrospect, I felt that Viacom delivered a decent channel to bring through the best of MTV and Comedy Central programming on Freeview at the time - which I enjoyed, but at the end of the day, they saw Channel 5 as a more viable vehicle for their presence in the UK broadcasting industry, and with that, saw no need to continue with Viva as a shop window. Sorry if that was a bit long-winded.