I think it's about time they gave up on themed areas as none of them save Katanga and Gloomy Wood (the only two Merlin haven't touched) are distinguishable as anything other than some rides with lazy themes cobbled together.
Galactica?
Rita?
Spinball?
Merlin bought Tussauds group in 2007.
Air opened 2001 in Forbidden Valley and didn't fit in the theming (and Galactica hasn't significantly changed anything).
Rita was placed into Ug Land in 2005 and didn't fit in the theming well.
Spinball was plonked into Adventure Land in 2004 and Adventure Land never had a proper theme anyway.
Battle Galleons was added in 2008 so could be seen as the first thing added since Merlin took over Tussauds and brought with it one of the best themed areas of the park. Sea Life opened 2009 and further improved the theme.
The Smiler theme added to X Sector, sticking with the life altering experiences and government secrecy type themes of Oblivion. The Black Hole that was there before it had a Jules Verne space theme out of sync with the rest of X Sector.
CBeebies Land brought together the old farm and storybook areas and improved them with a new cohesive theme.
Therefore I actually think in general the quality of theming was better in the last 10 years of Merlin ownership than it was in the 10 years before that of Tussauds. Although 1990s Tussauds stuff is still good, its just the 2001-2007 stuff that was poor.
Coming back to the Smokehouse, what evidence is there that this will ruin the theme any more or less than the previous courtyard barbecue?